? If exd5 with the possibility of c4 later on, you'd have prevented that pawn duo from marching down the board later on, also saved the time to retreat the queen
15... Nd7f6 16. Qd5c4 Qc7b7 17. e5 d5
! Wise to keep those pawns together instead of capturing. Also wins time by forcing yet another queen retreat .
18. Qc4b3
At about this point you need to start taking those c and d pawn seriously. They're linked and black succeeds in supporting them as they move down the board
18... Qb7xb3 19. cxb3
? Better to capture towards the center, which would also give your rook an open file
19... Nf6h5 20. Bf4e3
? How about Bg5? If 21. f6 then black ends up eventually playing gxf6, exposing the king. You're also asking for ..d4, forcing you to move this bishop again and losing another tempo
20... d4 21. Be3d2 g6 22. g4
? Don't do this before you have to. Knights on the edge are weak, and the squares it's supporting aren't important enough to merit this.
22... Nh5g7 23. Bd2f4 Ra8d8 24. a4
Don't you wish you'd gotten this pawn out of the way?
24... Rd8b8 25. Nf3d2 Ng7e6
! Chases your bishop (causing you to lose time while defending the c and d pawns)