WHERE DID I GO WRONG?

Move 23 was bad you did not have too push the pawn up pushing pawn's is bad.

Before 30. Nf6+ you should have moved Rd1 to protect the bishop. Also, not sure what purpose you had in mind with 45. Rg2, that move seems to have ruined any chances you might have had. Would have just moved the king to a safer location at that point.

I am hardly an advanced player, but I have found it to be of tremendous help to castle on the queen's side when the pawn structure has reached a formation in the middle like your own.  I often reach a position somewhat like that against the sicilian and against the Alekhine defense. 

When the opponent castles king-side, I normally end up pawn-pushing the G and H files and prying one of them open.  Sometimes it costs a knight or a bishop, but if the queen and rooks are properly stacked, the opponent finds their weakness on g7 and h7 to be a fatal one.

I also feel that your sacrifice of your dark bishop was unnecessary.  His dark bishop was about as useful as nipples on a boar hog.

Try this: try 17. h3 (or Be2).  If black takes your Knight on F3, retake with the Queen (in h3...bishop in Be2).  Then you can castle queenside (the only caveat being that I would not have pushed the A pawn as far..it's your weakest point on the board at 17).  Play back through it from there and see what you come up with =)

Disclaimer:  You're more than welcome to call me an idiot.  I've only been studying the game for about 6 months now.

You lost lot of tempo initially by giving check by Q and returning

8.Qd4+ had no purpose. 9.Qd1 lost two moves, at least 9.Qc2 would develop the queen. 13.Nb5 should have lost a pawn to Nxe4. Black's 13...Nb8 gave White a chance to save it, but after 14.a4 again it was there, but not taken. Instead of 13.Nb5, Qc2 was better. 18.Bg5 lost a pawn. 23.g4 was needed due to the pressure on f3, but 24.Nxd4 was optional. 25.f4 was good, preventing Ne5 or Nf6, but 26.g5 overextended White's pawns and the attack could not work.

 4.e4 instead of 4.e3 to solidy your hold on d5 and free te queen's bishop. You will find it necessary to move 10.e4 later to prevent Black from moving ....e5

8.Qa4 lost a tempo and gives Black the chance to develop a bishop while driving back the Queen.

12.Bd3 to protect the pawn at e4 instead of 12.Bd2 and enable castling.

14.a4 is a mistake. Better is 14.Bd3 to enable castling and protect the pawn at e4

18. Bg5, 26. g5 and 35. Rh6 are mistakes. 

i feel that simply put your queen was being overworked by protecting the bishop on d3 and the rook on h4. can be tough to spot especially when your eyes open wide to your possible mate. just stay focused and even if there's a mate within distance take some time to work out the details before moving ahead.

after around 8 and 14

Almost everything has been stated lol

I feel you were fine up until 35. Rh6.  I understand you were going for mate and it was a good move -- were it not for the Knight.  You should've ripped the Knight off the board with 35. Qxd3. 

I won't bother making you feel bad about the fork that occurs later in the game -- happens to everybody at one time or another lol.

Your opening was great as well.