Closed positions and opposite bishops - A tournament game retrospective

Andrew Merkel (1003) vs. Sanuka Ranatunga (unrated) [1-0] - Weekly tuesday night swiss tournament, round 2.
A game that turned into a closed position with opposite colored bishops started off as a normal London, but eventually I played 13. Bxf6 thinking that the queen cannot take due to xb5, but the pawn takes back and then we get into a position with opposite colored bishops. After black pushes some pawns on move 17. I decided to castle before playing a5, which was a mistake as it allows black to play a5 himself, although this move was never played in the game, instead playing 17... g3 18. xg3 19. Bxg3 (the mistake.) After this I expected black to be able to bring the queen to g5 and win my backward E pawn, so I played 19. Nf3, also a mistake as it allows the aforementioned a5 to be played by black. However, black missed this move again and instead played f6 trying to restrict my knights development.

Now after finally playing 20. a5 black plays 20... Qd6 looking to sacrifice the knight on b4, which I saw, and responded to with 21. Qb2.
Then after trading down black plays 25... e4 attacking the knight, missing Bxc4 (which I did not play as it seems as it is quite an dubious move to play, trading a bishop for 3 pawns). Instead of Bxc4, I played 26. Nd4, black took, and I took with the rook. after 28. Be3? (a mistake) I can get my rook back on the first rank and connected with the other rook, and after 29... Rf8?? I am able to win blacks bishop with 30. Bh5+!. after this we traded pieces down to a winning endgame for me and I won the game 1-0.

 

In conclusion, we see how opposite colored bishops can greatly benefit the attacking side when other pieces such as rooks and the queen are still on the board, and aswell what to prioritize in a defense. I saw that black playing a5 would allow black to get his queen involved and I still ignored it and I most likely would have lost the game if black saw the move. This game was quite wild, and serves as a good reminder of these topics of opposite colored bishops and closed positions. There is one more round of the tournament left, and hopefully I can win that to go undefeated. I will most likely do another review on that game when Its done.
If I missed anything feel free to comment it, and have a great day!