Material vs Attack

Just simply winning a Bishop seems like a no brainer to me. You're only giving White new hope by not doing it. Your note "There is still a considerable amount of tension on Black's queenside." doesn't make any sense. Everything's great for you and it should be an easy win.

White has no attack whatsoever after you win the bishop.  White cant play bxb or you exchange queens before recapturing, and white has zero attack.  If qb3, you play e4 and the attack is yours.   

You outsmarted yourself.  A very common thing to do. 

Thanks for your comments everyone! I've learned quite a lot. 

I completely missed that mate, too. Thanks, Paul- looks like I'll have to go back to chess puzzles soon. 

edit: When I sent this game for computer analysis, it played 23. f3 in response to Qd5. Now I know why.