Would somebody mind taking a look at my game that I annotated below. I am having difficulty understanding a few of my mistakes. (Namely on moves 5,7,12,17). Thanks.
[FEN ""]
1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.Nf3 O-O {This is the Nimzo-Indian Three Knights Variation.} 5.Bg5 {My goal with Bg5 was to pin the knight to the queen in order to prepare for e4. Supposedly it is better to just defend d4 with e3 but I don't see why that is.}
( 5.e3 b6 6.Be2 )
5...c5 6.e4 d5 {...d5 is a bit of a blunder because it then allows e5 to attack the knight.} 7.e5 h6 {Bh4 may have been better here. I was imagining that after Bh4 black could then play ...g5 to chase my bishop away and then give him time to move the black knight.} 8.Bxf6
( 8.Bh4 cxd4
( 8...g5 9.Nxg5 hxg5 10.Bxg5 )
9.a3 dxc3 10.axb4 cxb2 11.Rb1 dxc4 12.exf6 Qxd1+ 13.Kxd1
( 13.Rxd1 c3 14.Bd3 Nc6 )
)
8...gxf6 9.Bd3 {This is a blunder if black would have seen it.} 9...h5 {This is a nice blunder by black that allows me access to the kingside. Though for now castling is the right move.}
( 9...cxd4 10.Nxd4 fxe5 11.Nc2 Bxc3+ 12.bxc3 dxc4 {It is difficult for me to see why this line makes Bd3 such a blunder, but it could just be because it makes a mess of my queenside pawn structure. But to me this does not look like losing because I can still castle safely, and black's kingside is a mess. Perhaps there is a tactic black has that I am not seeing. It could also be just that I am down two pawns.} 13.Bxc4 Qxd1+ 14.Rxd1 Bd7 15.O-O )
10.O-O cxd4 11.Nxd4 dxc4 {This is a blunder that allows me to get into the kingside.} 12.Bc2
( 12.Qxh5 {Getting the queen into the kingside early is quite advantageous. I did even feel that I was just holding the queen back for too long while worrying more about other moves.} 12...cxd3 13.Qg4+ Kh8 14.Rad1 Rg8 15.Qh4+ Kg7 16.Rxd3 Ba5 17.Rfd1 Qd5 18.Rg3+ Kf8 19.Qh6+ Ke7 20.Nxd5+ Kd7 21.Qxf6 Re8 22.Qxf7+ Kd8 23.Qf6+ Kd7 24.Rg7+ Re7 25.Qxe7# )
12...b6 {Be4 if a good alternative to Qxh5 because it exploits black's blunder exposing the rook, but still moving the queen into the kingside is far better.} 13.Be4 Be7 14.Bxa8 fxe5 15.Nc6 {Nc6 is actually the right move, because it forces an exchange with my knight. I was unsure if this is right because black has the option (which is the best option it has) of exchanging the knights when its knight was not even developed in the first place, and therefore slightly weaker than mine.} 15...Qd6 16.Nxe7+ Qxe7 17.Qxh5 {Here I finally capture the h5 pawn, but I should have done this a few moves earlier. Though there is still a blockade into black's kingside which is advantageous to me.} 17...Na6 {Here I was thinking that it would now be best to get a rook into the black kingside, but was trying to figure which rook was better to move. I was thinking that if I keep my f1 rook where it was it could provide some defense if black's f-pawn could ever capture away from its file and then the queen and rook could double up and attack my f-pawn. But I decided that it was best to have the a1 rook on the queenside to defend my two pawns instead. (Apparently the right move but not sure of the logic.)} 18.Rfe1 f5 19.Re3 Rf7 20.Nd5 {This is the right move, I was figuring that I could try and push the queen away from the kingside fight if I put pressure on it. If black captures, I can then pin the rook to the king with my bishop.} 20...exd5 21.Bxd5 Be6 {Here I was having difficulty. I was thinking there had to be some checkmate (which there is in 17 moves) but I just couldn't see it, so I figured simplifying would help.} 22.Qg6+ Kf8 23.Bxe6 Qe8 {Miss a M8 here which I almost saw. I was thinking through about 4-5 moves in the mating line, but just couldn't quite see it.} 24.Rg3
( 24.Rh3 Ke7 25.Rd1 Nb4 26.Rh8 Nd5 27.Rxe8+ Kd6 28.Bxf7+ Kc7 29.Bxd5 c3 30.Qc6# )
24...Nc7 {Just figure trade off some pieces and gain material and figure out the checkmate later.} 25.Bxf7 Qxf7 26.Qxf7+ Kxf7 27.Rd1 Ke6 28.Rg6+ Kf7 29.Rc6 Nb5 30.Rd7+ Ke8 31.Rh7 Nd6 32.Rxd6 e4 33.Rc6 a6 34.Rc8# 1-0