Embarrassing Ending

BACK at Bradford for a three-day, five-round U171 tournament, which I won in 2016 and did horribly in last year.
My round-one game this evening was reasonably played on both sides ... until we reached a king-and-pawn-ending.
Richard Desmedt (144) - Spanton (167)
Stonewall Attack
1. d4 d5 2. e3 Nc6 3. f4 Bf5
Chigorin played 3... Nh6 at London 1899, drawing with Showalter and losing to Tinsley.
4. c3 f6!?
Hoping to smash White's central wall with a quick ...e5, but ...e5 does not
come until move 19.
5. Nf3 Qd6 6. Bb5
This may be a new move. 6. b3 was played in a Swedish game by a 1959.
6... a6 7. Qa4 Rb8 8. Bxc6+ Qxc6 9. Qxc6+ bxc6

The queens have come off early

White has stopped a quick ...e5 and has broken up Black's queenside pawns, but at the cost of giving up his good bishop.
10. b3
An exchange of dark-square bishops must help White.
10... Nh6
Nevertheless it might have been better for me to play 10... e6 11. Ba3 Bd6, so that 12. Bxd6 cxd6 would reinforce Black's centre.
11. Ba3 a5
Hoping to prove a weakness at b3, but I had not seen far enough ahead.
12. Nbd2 a4 13. Ke2 Kd7
13... axb3 14. axb3 Bc2 is no threat as I cannot capture on b3 with my bishop because of a subsequent pin along the b file.
14. h3 e6 15. Bc5!?
My main analysis engines Stockfish9 and Komodo9 slightly prefer 15. Bxf8, but they do not hate the text.
15... Bxc5 16. dxc5 Rb5 17. b4 Re8 18. Nd4 Rbb8 19. N2f3
The engines give 19. g4 Bg6 20. N4f3!? with what they reckon is a roughly equal position.
19... e5 20. fxe5 fxe5 21. Nxf5 Nxf5 22. Kf2 e4 23. Nd4?!
Although the engines reckon White can get away with this, I thought it was rather risky.
23... Nxd4 24. exd4 Rf8+ 25. Ke2 Rf6 26. Rhf1 Rbf8 27. Rxf6 Rxf6

A difficult position for White, whatever he plays

28. Rf1?
The king-and-pawn ending should be lost for White with correct play. But even if White keeps a pair of rooks on, Black can carry on probing.
28... Rxf1 29. Kxf1 Ke6
My original idea was 29... Kc8 30. Ke2 Kb7 31. Ke3 Ka6, which does indeed
seem to win, but the text is fine too, although it requires more-precise play.
30. Ke2 Kf5 31. Ke3 h5 32. g3 h4?
White is in big trouble after 32... a3, eg 33. h4 g6 (but not 33... Kg4? 34. c4! Kf5 35. cxd5 cxd5 36. b5 with a draw) 34. Kf2 Kg4
33. g4+ Ke6 34. Kf4?
34. a3 seems to draw as neither side can make progress.
34... Kd7?
Again 34... a3, and if 35. Ke3 the engines give 35... g6, eg 36. Kf4 g5+ 37.
Ke3 Kd7 with lines similar to my original idea of 29...Kc8
35. c4?
35. a3= K9/S9.
35... dxc4 36. Kxe4 Ke6?
36... a3 is still key, eg 37. Ke3 Ke6 38. Ke4 g5 39. Kf3 Kd5 40. Ke3 c3 41. Kd3 c2 42. Kxc2 Kc4! and Black wins (K9/S9).
37. a3! g5 38. d5+??
38. Kf3 holds, ie 38... Kd5 39. Ke3 c3 40. Kd3 c2 41. Kxc2 Kc4 (or 41... Kxd4 42. Kd2) 42. Kc1! Kxd4 43. Kd2 and White draws thanks to having the opposition (K9/S9).
The game finished:
38... cxd5+ 39. Kd4 c6 40. Kc3 Ke5 41. Kd2 Kd4 42. Kc1 c3 43. Kc2 Kc4 44. Kc1 d4 45. Kc2 d3+ 46. Kd1 Kb3 47. b5 Kb2 48. bxc6 c2+ 49. Kd2 c1=Q+ 0-1