10...Nf5 looks an improvement to me. 11.Na5 Qc7 12.Nc5 ? b6 is going nowhere, and g4 would weaken the kingside.
12.bxa5 Qxa4 13.Qxa4 Bxa4 14.Bd3 followed by Ke2 and Rhc1 and I prefer White in this endgame (space + b file), though Black should hold this.
The position at 18. is much better for Black in my view, not "completely equal". White has an awful c1 bishop, Black will soon play ...b5 locking the knight on the c file, and then can choose between play on the queenside by opening the a file after preparation, or on the kingside with moves such as ...h5 ...Nh6-g4 ...Qd8 ...Rg8 ...g5. Meanwhile, I do not see any plan for White.
I prefer 25...bxc4 without a "weakness" on b5, but that's wrong taste from me. 25...dxc4 (text) allows to put a piece on d5, it's valuable too.
Here is the fully annotated game and I sure hope you all enjoy the game and the comments. I always try to comment in a way which will make things easy enough for all levels will be able to understand. PLEASE PLEASE READ THE ANNOTATIONS before you ask questions. They are the whole reason I write the comments I write.