basically your op was able to get his q and rook in your kings side. 3 fold was possible at that point. pure and simple. but i am no expert.

knight at b4 was wrong (the other knight outpost was OK )
14 ~15 castling you could exchange a knight c3 for a bishop, small material win.
better then the knight-knight exchange later, it might have some advanced background idea, but how about the simple chess rules knight is lower then bishop. (i know we could talk about that a lot, but its for 80% true, thats enough to me)

24.. the way the black queen flees for the knight..
maybe Qh4 would have been better, know the general safe positions against knights

26..parking a bishop next to a pawn.. as a 1700+ player ?

35 to greedy loosing the rook too quickly , .. later going for draw.. the wrong chess spirit.  (instead you might have checkmated from 31 if you didnt went for the knight)

Overall to be honestly i dont see why black should have won this game, from both to much mistakes, white plays way to defensive (white should be the first agressor on the board), black to much errors but i dont want to hurt you thats how i would rate myself if i played like this (in white or black) although i'm just a 1190 player. It does remind of lower ranked players (who i dont like to play because they miss understanding of the game theoretics and so they play non logical which is confusing to play against. (but then your both 1700+?) maybe both had a bad hairday,  be glad you didnt loose to much points since the other player was almost at the same rate, a 1300 player or me (in a good shape, might have won this, with checkmate as black or white).