What went wrong I need some advice.

Firstly, you point out a fact that most people won't tell you about a weakness: if you can't exploit it, it really isn't a weakness. IRL, I'm missing part of a leg, a weakness to be sure, but at a chess tournament, you'd never be able to use that against me, but playing basketball, you could exploit that by going to my left.

On move 27, the h-pawn is on a square that you can attack it with the bishop, yet you moved it in the opposite direction, although it did provoke another weakness. However, on h5 you can attack it three times; rook, bishop, and pawn.

BTW, www.youtube.com/watch?v=yLrNC9Rskww&list=PLW-ubDuosu7UKDXI6KF7XIMdzaStaVEIL is a reading of My System by Nimzowitsch. www.youtube.com/user/STLChessClub has many useful videos. I hear good things about www.youtube.com/channel/UC6hOVYvNn79Sl1Fc1vx2mYA and www.youtube.com/user/brendanjnorman.

@Anon5005 Whenever your opponent has a weakness you should be always aware of it. If you attack it and the opponent defend it, this at least means you have the initiative. If you can attack twice a weakness, you force your opponent to defend it twice, this means those pieces are leaving other parts of the board vulnerable. I agree with @jonesmh, that was a key moment in the game.

BTW, move 30 was a mistake. h3 would have "forced" f5 and allowed you king to enter the game.

As another example, the doubled f-pawns are considered a weakness, but being so hard to attack and providing useful coverage in the center, they would be thought of as being strong. However, 22. fxg3 does expose them to a (useless) frontal attack. Objectively the move is not a good as capturing toward the center (which would have increased the space for a frontal attack of the h-pawn if you had another rook, and provided the rook with an easier retreat), but it does have some merit.

Psst, ever heard of the principle of two weaknesses? You won't win with one weakness which can be defended easily.

First idea when I saw the game: totally misplacing the rooks in order not to win the h6...

@jonesmh Your spot on with the bishop I should have attacked the pawn with the bishop my Bc4 move was not constructive at all. Thanks for pointing that out and the video recommendations. The mistake with fxg3 will not be made again you explained it well. About h3 that one I would never spot I was hoping on en passant to straighten my pawns (hope chess). Thank you very much for taking your time to explain why things where bad and what would be better.
@etaLaskera Thanks for the comment.
@Sarg0n Yeah I have heard of that rule but not that easy to create a second weakness in practice for low rated players.
In matter effect not that easy for strong players either.