11. f4 I fancied my chances after the exchange and the open f-file that I would get if it occured.
I think you've accurately identified the turning point in the game here. 11. ... Bxg5 is a mistake. Black should probably play Bd7 and castle long. He can try doubling the rooks on the h-file. At some point he may want to play f6 and g5 to try to open the diagonal leading to h2. That looks like a much better plan to me than giving you an open line to the weak f7 pawn and leaving the king in the center.
I was able to capitalise on his only mistake 16.. Bb7 , and was able to force a win from there . I hope you like the game