You're too concerned about material. Moves like 20...Qxb3? gain material advantages at a huge positional cost. Taking the pawn takes away the strongest defender of your king and doesn't do anything to repel white's attack. 20...f5 was more solid. Another example of this was 18...Nf3+?, exchanging a knight for a rook, but actually a trade that didn't favor you. His rook was completely inactive and non-threatening, and your knight could have been a serious threat after 18...Qxh3. Also I'm not sure why you played 15...Qe6, 15...dxe4 solved the threat without losing tempo. Like you pointed out, 23...f6?? lost the game.
An OTB game I played...
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There are only two points that I must contend with.
Qe6 was nessecary to keep control of the center.
And Qxh3 looks grim for white, and it is psychologically debilitating, which is a tactic that I like to use in OTB chess, but as far as I can see, there is no mating threat that white can't easily avoid.
Plus, there isn't much scarier than having someone sac a piece, right? (Well, perhaps unexpected checkmate but...)
dxe4 strengthens control of the center by giving the rook more control over the newly open file
Qxh3 is followed by Ng4! threatening mate, as well as clearing the diagonal for you to take the rook for free.
18...Qxh3 19.[insert random harmless white move in replacement of Bg2] Ng4 20. Rb1/a2 Qh2+ Kf1 and Qh1 is horrible because of Bxh1.
that's why after Kf1 you play Rxe4. Then, if Qxe4, Qxf2#. And let's say white does play 19. Bg2. 19...Ng4 20. Bxh3 Rxe2 21. Rxe2 Bxa1 22. Bxg4 Rd1+ 22. Kg2 Rxc1.
Fair enough.
What do you think I could improve on, aside from not walking into devilish traps?