Thanks very much to both of you for the comments

@Bill:

-- yes, I wondered about the bottom left and let Black play up here. Maybe just a different game? I really don't know, this was one of those "which do I do?" moments

-- Ah yes, that makes a lot of sense, I must admit, I was sort of hoping to create the top left situation when I approached from the side I did, but I suspect the fight was unreasonable, and I suspect that if Black responds simply on top then it's not even a good exchange compared to your idea

-- Yes, ok, I might have jumped the gun here. Certainly, it was messy, and could have ended up badly. Probably better to play in the bottom left. I didn't really want to exchange your third option in sgf, just because I didn't want to kill the aji. Maybe securing my upper right group is playable with the threat of the move I played? By

I was definitely feeling like I'd gone in too soon.

-- Thank you, this is very insightful. I'd been agonising about M3 for a while, it just felt like it let Black build this big framework, and if Black got Q2 as well, I felt like I was falling behind in the midgame. As you say, with M3, I have potential of my own. I think I'd have been more inclined towards it if E3 was already on the board.

-- Thank you again, very useful, this was another move I was agonising over. It felt possibly too soon to go towards O3, I'd just felt like I'd have been losing points if Black got M3 (which may have been the problem with not playing it myself at move 68.

-- Thank you for this one too -- another agonised move. I'd actually decided that I was low enough on eye space I had to dangle some bait, and let it get sacrificed in exchange for some kind of thicker shape. My thoughts were either I get another move and my shape is nice and the reduction is good, or he cuts it off, and I settle the group albeit at some territory cost - is this basically my bad habits coming through?
@Dave:
I've enclosed my (optimistic?) reading if Black went for the kill. I frankly was greatly struggling with the reading depth over the board. I had assumed at some point Black would return to mutual life, but without giving me the very nice top right corner.
EDIT: Yes, some of my exchanges would have made great local ko threats -- I thought a ko immediately looked unfavourable for me on liberties though, so I was sort of trying to avoid it. Having said that, at the end of my line, I'm still on one eye, and Black can live in one move. I'm unconvinced I'm getting counterplay on his central group - even if he forces me to live by strengthening it, he seems to have come out of the exchange rather nicely. This fight was one of the two big reasons I wanted to post it here. So hard for me to get to grips with the complications clearly
