4: Pretty boring, and the kind of shape that white can turn into a bad move later. R3 is easier locally, but you can just tenuki if you want. This move is quite boring.
10: This way is not usually great (though it's hardly game losing), as you aren't very strong in the lower left. White C10 is too easy for him to get away with. C11 is easier.
20: Pushing from behind. I don't see a reason not to jump to G3.
26: A rubbish move. It leaves shape weaknesses everywhere, doesn't protect your base, and asks white to finish his weak upper position - it's a thank you move. I think C12 is best here, white's C11 stone is weakened and you probably have 2 eyes locally (certainly, if white can stop you having them, he can't do it easily or in sente. There is no need to be clever.
28: Go the distance, or don't go at all. L17 threatens to undermine white's extra long extension. P17 (or similar) protects the corner. M17 does neither very well.
29: White makes the same mistake, I think.
30: Doesn't protect the corner, doesn't get into white's position. Again
32: And now you can block this way and get no territory, or block the other way and be horrendously overconcentrated. You must look ahead when playing moves like M17, because this situation is easy to foresee if you know it can happen.
44: Did you consider moves like G17? You have to try and make this sort of thing work. I don't know if it actually does
46: Why? What does this move gain?
48: Because now you feel obliged to play this very small move to save that stone. Other points, like R3, are far larger. I wouldn't be surprised if you could play something like R6, to take advantage of white's large extensions.
52: Not incredibly small, but...quite small. You are worried about white making 10 points or so in gote here, when the lower right is much larger. This is something to understand from experience.
54: Aww! So small! R3 is much better.
56: So now you help white fix his position which you just made strong by playing R3, without getting any points in the process.
I'll stop here. The general theme is, your moves don't go the distance. You fix white's position for him without helping your own position. Moves like F14 are unnecessarily scared. Moves like K17 are insufficiently sharp. Moves like Q3 lose a really significant number of points (especially in the context of a 10 point loss, which can be made up in the endgame with moves like this). All your moves were normal, for you, but normal in a way which slowly drains your lead and turns it into a 10 point loss. Sharpening your attacks as I have suggested should help keep your points, and take them from white instead.