Lots of great advice already!
Maybe my approach to study and getting better might be interesting, too, since
** I've been stuck at about the same level as the OP with a little glimpse of overcoming the barrier last summer (but not succeeding because I had burned out then and took a break and was where I left)
** I've also been a member of Yunguseng Dojang
** no matter how frustrated I've been in the past about my (in)abilites in this game, I never was able to turn my back at it. Never wanted to seriously do it either and I never gave up on wanting to progress. I do admire everyone who has made his/her peace with his/her abilites and is content with what has been achieved. I couldn't accept that yet to this very day for me (maybe stubbornness issues..?

), I still want to go on but I felt paralyzed, like arubber band pinning me down where I am. Might enjoy a short glimpse of the stronger rank but then crash down again. Last year I realised that I had to change both my approach to studying as well as my approach of the game towards enjoying it more instead of beating me up for that disheartening situation where I thought nothing would or could help me to be able to do it. Sometimes you have to experience it and no matter how many times people tell you something it's no shortcut to really understand it.
This is quite some wall of text and it's my very personal way to tackle this wall. There is no 100% formula to rank up in this text or in general, too, everyone has to find his/her own way to do it from a certain point on when it's starting to get hard. So keep in mind that's my approach and it (looks like it) works for me, it might be different for you. But maybe some parts of my way are helpful for you. If you want it quick and dirty, go to the last two paragraphs.I've also been frustrated a lot about not progressing for many years although I had the impression I was working quite a lot on my Go - and therefore was expecting some change, just like you. 2 years ago, I started bullet journaling and I really liked it a lot and I thought why not use it for Go as well? In the end the result of tracking my efforts was quite embarrassing: I did WAY less than I thought but still had expected my rank to raise constantly because I was watching the lectures and playing the league games and watching the reviews. Seeing in the tracker the meager amount of work I put into Go I finally realised that my perception and the reality were quite different and that what I'm currently investing is not going to get me anywhere.
Last year I tried to use the bullet journal to force myself to play more, which, according to In-Seong, is what I need to progress: Get more game experience. In the end I failed to reach my target number of 200 games (20-25 minutes base time minimum + byo) by a relatively close number but I learned many lessons much more valuable than that game experience I obtained. Some things are included here that I already read about many times before but didn't experience and therefore thought not as much of as I do now. Sometimes, you gotta experience it and no one can spare you that. My top 7 takeaways are:
1. I need a constant effort. I'm talking about 10 minutes of tsumego a day here as a bare minimum. I CAN do more, but should try to never miss those 10 minutes. I prefer the Cho Chikun Encyclopedia because I can use my printed copy and because they don't have solutions in them. I also try not only to read the solution but as many branches as possible - because the training is about the actual reading and not only about the solution. It does take quite some time for me to actually see the progress, probably the same for you. But, as all study, it does pay off in the end.
2. As a procrastinator it does help a LOT to break down large goals into small, bite-sized chunks (helps also when you're not procrastinating!). X games/reviews/minutes of tsumego/pages per week is something I found very helpful.
3. I have to take into account my strengths and weaknesses and create a study plan to work on my weaknesses and bad habits I am struggling with - In-Seong's reviews and especially the personal report is GOLD for this. Have you already received one? Cannot recommend them highly enough! Take it as a roadmap of where you are now and make a plan. Pay the smallest bars most of your attention. Everyone has to work on his/her own weaknesses, so this is very subjective but going about it in a planned out way I felt some progress after 4 weeks already: I have recently studied basic shapes a lot and I was over the top when last weekend I could kill my opponents corner group actually quite easily. If you know where your weaknesses lie you will see some quick progress, if you do what you're already good at you won't because the bad parts will always drag you down again.
4. There are goals you have influence on and there are goals you just haven't. Can't force a server to make you Xk/Yd because you want to and without proof/winning ore games. If you focus only on goals that are beyond your influence like "I will win the next 10 games" or "I will be rank X by end of the year", you're sailing in dangerous waters and will probably sink sometime soon. Not only will it drain you from all the fun and motivation you might have, you're probably going to develop an obsession with your rank and this is not helpful at all. I'd recommend to focus on goals you can measure and influence like the amount of study you put into, the number of games you play etc. If you keep at that, then progress in the form of a stronger rank will be a byproduct of it. And you'll be very proud of what you did if you look back after some time and enjoy yourself a lot more.
5. The mindset is so important, too. I'm still struggling a lot with this one as I've been kinda obsessed with ranks and ratings myself, which made me anxious about many things related to Go, playing online probably being the most important one. Imagine fearing what you actually want to become better at.. it's pretty ridiculous! But fears are never rational and just like bad habits overcoming them is quite some task. For me that's probably the most important thing that's holding me back at the moment, my fear of doing something stupid, of not getting enough points, of losing streaks which might hurt my trust in the process etc. Last summer, when I had played a lot and didn't feel like dragging myself to the digital board several times a week but instead logged on in a good mood, I really noticed a difference and In-Seong noticed it, too. That was a happy moment! But because my planning had been bad at that time, I tried to do too much in too short of a time and kinda burned out. In the end, I couldn't keep up with it, ending up frustrated and doing nothing for several weeks. After that, I was standing before that familiar brick wall again...
6. You've been playing Go for some time and you've been stuck for some time, just like me. We both reached a certain level of proficiency. Progressing from that point takes time, changing your bad habits will take effort and time. It can't be forced or squeezed in a certain frame of time, that's something you got to accept. It'll depoend to some degree on how much you invest and how useful the methods are you are using. Thinking too much about ranking up takes away ressources you better put into things you can influence like your training - progress will come as long as you're working towards your goals. I fight my impatience by focussing on the progress I make with my studies instead. Seeing what I already did and achieved since this year began and successfully applying things I learned in games makes me proud and makes me think less about if I should have ranked up or not. That'll come in due time. It's way more fun to look at the game like this, too. Thinking that way has taken quite some time for me because of me focussing on ranks - just like in Go when you have a fixed idea it can be hard to break that. Tracking stuff is helpful for me to bridge the time until I have "built enough muscle" to show in a rank change. I'm not expecting to see that in the next x week. Can't force it, I'll only imagine it to keep the motivation up. And enjoy the moment when it comes to the fullest.
7. Having someone who shares your passion is making the adventure much more fun. Maybe you can find someone of similar ambition and strength to play a serious game a week, review together, have a good chat when things are looking down - or up! - encouraging each other. It really helps to stand the slow crawl and even enjoy it, for both of you.
You say that you play 1-2 games per week and review them with AI. It's great that you're playing slow games and review them with AI, but as someone said before me, with this "speed" reaching your goal will probably a very slow walk (or rather crawl). I'd definitely recommend 4-5 games/week and, very important: Try to incorporate what you learned in the lectures. I know that this is sometimes easier said than done, but the more you play the more chances you'll have to apply your knowledge. I'd also focus on few lectures/new things and instead study them thoroughly. It's ok to go slow if you understand it. If you do, then forgetting the exact pattern is not a big deal because you learned the general idea before and can come up with the solution if you need to. This is way more valuable than cramming a lot into a short time and not taking enough time to digest it.
So my advice would be to first do what gennan suggests above and if you love this game and are adamant about progressing and not just want to reach Xd and then stop playing (which would be a ridiculous thing to do in my eyes, what's the point in that?), then
** look at what weaknesses you have - how can you work on them effectively and which ressouces (books, Yunguseng lectures, stronger players, ...) could help you here?
** think about how much time per week/day you're able and willing to invest on a regular basis. Be realistic here and keep in mind you're going for a longterm goal. Can you imagine doing that in 1 year from now, too?
** then think of some SMART goals (you might want to google that if you don't know about the smart idea) make a plan based on these goals, splitting them up in digestable bits. Start small, be consistent, create good study habits, increase the workload if you feel (too) comfortable. But always do the minimum. Stick to the plan for some time, let's say 4-8 weeks at least, then check how you feel about it and think about if you need to make some changes. If you notice something good. And: measure what you are doing (might track the good things happening as well, we tend to forget about the good stuff and focus on negative things).
** try to shift your focus on things you have influence on. Things you enjoy about go. Find pleasure in being able to apply your knowledge, in outwitting your opponents with what you learned. The rest is not important so you shouldn't pay it much attention.
I gotta admit I haven't been doing it for a long enough time to have any "real" proof that this is working. However, I'm starting to feel good coming from it and am confident that I'm on the right way. Always remember: It's a marathon, not a sprint. Might as well enjoy the sights along the way, pick a few flowers, have a chat with the people you're meeting and from time to time look back on all that has happened in the last few months/years, be amazed how you suddenly ended up here and then turn around again and focus on that far-off goal in the future. And if in the meantime you're walking through the desert, like you are now, suffering the heat, the thirst, the sunburns and all the other uncomfortable things you might experience there (scorpions!!

): keep walking - or you'll stay there. This always your choice to make.
