More tactics. For example, instead of 27...Rb2+ winning a piece you had B:f1+ winning a rook. Also on move 18... white had two hanging pawns after playing a self interference, but you didn’t take either one. If you don’t snap the c4 pawn off in a blink of an eye it means you gotta focus on tactics, not opening prep.
I liked your ...kg7 idea to get a rock to h8, but be careful in Nimzo doing the whole ...h6,...g5 thing, it weakens your kingside, it can become dangerous if white focuses on your g5 pawn.
Old school strategy of focusing on white’s doubled c-file pawns was available to you here, try this strategy when white has those doubled pawns: Black bishop to a6, Knight to a5, and you got two people on c4. Often you can win a pawn that way.
Watch a Nimzo youtube, or better several.
Maybe you could have played ...a5, then ...Bc8-a6.
Or, ...Bb7-c8-f5 or g4
I don't know, but you lose a lot of tempi with your bishop.