Honestly I think white has too many draw threats.
36... Kh7 37. Qf4! Bd4 38. Qf5+...
I think your best chance at a win was 36... Qd4!
This threatens 37... Rxf1 38. Kxf1 Qd1#
It also wins whites powerful d pawn. The best response for white in this situation is the following line.
36... Qd4 37. Qc8+ Kh7 38. Qc2+ g6 39. Kh1
Here is a diagram of the position.
Here black has some mating threats with Be5 followed by Qh4. Or you can play for the end game by simply picking off whites pawns.
What should I have done, Kh2 at ...36?