Hello, this is my best win on Chess.com and I'm hoping for some helpful analysis of what I did well, what I could have done better, etc. Thank you!

My thoughts on your game:

Good job on the endgame, but opening and middlegame could use some work.

I would pursue 12.... Nc6 followed by Qa5 and cd (d4 if he takes dc). Your opponent has outdeveloped you at this point of the game.

You have to do more to exploit the weakness on c3. 13....Qa5 followed by Nc6 is better. You prevent his rook and queen from moving. The c3 pawn is pinned so if the Queen moves, you can take d4 with the knight. This also keeps him cramped and gives you time to catch up in development. If 13....Qa5 Nf3 14. f5 ef 15. e4 is strong. 

16... Kd7? Don't put your king towards your opponent's open file 

funny thing about the french the king if quite safe is the closed center

16... Kd7 is fine.  And the suggested 13... Qa5 14 Nf3 f5 15 ef e5 meets with 16 f7+ Kxf7 17 Nxe5+.

Thanks for the responses! As you can see, I played this a while ago, so it was interesting going through the game. It's amazing how different the game looks when you're not actually playing it. I kept hoping I had played 19... fxg3, and then 20... fxg3, etc. It's amazing how obvious it looks in hindsight.

Any other thoughts? I feel for the most part I played pretty well, but I know I can always improve. I think as a chess player my biggest weaknesses are a. forming plans and b. changing them when appropriate.

Yeah, that's always true for me too.  Sometimes I can hardly even believe it was me playing the moves!  I always seem to be in a rush to make things happen during a game, and then afterwards I see I could've relaxed and taken it a lot slower.