I definitely think you're winning after move 13. Your opponent's pawns are just abysmal. Nice play to there, now let's go on:
Ok, moves 13-20, you put your pieces on sensible squares, won the weak pawn - You're still ahead here. 21...f6 seems a little pointless, just weakening your pawns by providing an easier target for your opponent in my opinion, you're not going to trap that bishop. 23...e5 seems a little illogical if you're playing for the d5 break, better was perhaps retrieving the bishop with Bf7 (actually making use of your move f6) and then playing e6 setting up d5. I know you're not supposed to place your pawns on the same colour as your bishop but the position is going to break open anyway so here that was perhaps a better plan.
24...d5 - this came before you were prepared for it I think. You had time to double your rooks or maybe should have done this before instead of weakening moves like 21...f6. Anyway back to 24...d5. After the rook recaptured, he pinned it and you had to resort to desperate measures to try and extricate it. I say desperate because I don't think 27...f5 works, what about the continuation 28.Rd6! Qxd6 29.Qxc4+ Qe6 30.Qxe6 Rxe6 31.Rd8+ and White comes out on top I think.
After what he did play, you were fortunate to get your rook back, then he blunders awfully with 30.Qg4+, and you didn't take the queen!? You may have meant to put in Qg5+ here perhaps?
After that you had no hope. Summary:I thought you played well in the opening stages, but then lost your way breaking open the centre. The most important factor was that you had time to prepare d5 properly and make sure all your pieces were focussed on it.
though! I'm in a no-games moratorium...
Eventually, I lost this game in which I found myself with a (what I think) winning position after move 13 (I am black in this game). What I would like to know : my strategy was to focus on the 3 doubled pawns and try to gain one or two, and then try to open lines for my rooks. I only managed to get one pawn though, and after opening the files for my rooks, I missed a tactic and lost the endgame.
Loosing with the tactic can be learned (don't miss the tactic!), but again, I am eager to learn how to play this position after move 13.
Here is the game.
I still have to analyze it myself, so no annotations yet.
Thank you,
Kristof