Your 8...Bb4+ looks like a strategic mistake. Why do you want to trade your good bishop for his bad bishop? You will remain vulnerable on the black squares for the rest of the game.
Your 11...Kf8 also looks wrong. He offers to trade his good bishop for your bad bishop and you decline the trade. Just 11...Bd7 is fine. You do not have to fear doubled pawns after double trade on d7 and f6, as the open g-file is enough compensation. His good bishop will come back to checkmate you with 24 Bh5. At that point you might have wished you had traded it away 13 moves earlier.