Mistakes in my game

Question

I would like to receive some feedback on my mistakes of the below Lichess game, if possible from someone above 2000. I an unsure about the reason of the mistakes I did in the game. When I finished the game I thought I had won quite convincingly, but apparently, I made some mistakes early in the game. I was playing with the black pieces.

[Title "ulimilu1997-bird67, lichess.com, 10/11/19"]
[FEN ""]

1. Nf3 Nf6 2. Nc3 c5 3. g3 d5 4. d4 cxd4 5. Nxd4 e5 6. Nf3 Nc6 7. Bg5 e4 8. Nd4 h6 9. Bxf6 Qxf6 10. Nxc6 bxc6 11. e3 Bb4 12. Qd2 O-O 13. a3 Bxc3 14. bxc3 Qf3 15. Rg1 Rb8 16. Be2 Qf6 17. Kf1 Bh3+ 18. Ke1 Rb2 19. a4 Rfb8 20. Rc1 Rb1 21. Kd1 Qxf2 22. Qe1 Qxe3 23. Bh5 Rxc1#

Mistake in 7th move:

I played 7... e4. Later, I realized that d4 was probably better but I get the feeling that after 7... d4 8. Ne4 Be7, Black has lost some initiative.

Mistake in move 8:

I played 8.. h6 as White’s Bishop is forced to be exchanged on f6 or to retreat to a passive position. I calculated 9. Bxf6 Qxf6 10. Nxc6 bxc6 with a more or less favorable position in which the powerful center, which will be stronger after c5, is an advantage for Black. However, Stockfish evaluation drops around 1.

Blunder on move 11

I played Bb4 threatening to win a pawn. However, it is considered a blunder. I do not understand this. I do see that 12.Qd4 forces the Queen trades, but to me, the position is not much worse for Black for it.

Blunder in move 13

Given that the g3 pawn of my opponent is on a dark square, I thought of trading the bishop. I now realize that maybe this bishop had some prospects on the g1-a7 diagonal, but again I am not sure why this qualifies as a grave mistake.

Note: If possible, could you please also tell what move number you would stop at in order to calculate variations? I am unsure if I am doing this at all, but all my calculations take only 6 moves at best by each side. I know that in the middlegame, I should probably do some analysis of variants but in games I am not sure how deep these analysis should be.

Answer 1

Here are my thoughts on that game. Sorry, after a long day, I tried to format it correctly in a board.

 [title "Annotated game analysis"]
 [fen ""]

 1. Nf3 Nf6 2. Nc3 c5 (2... d5 {Why not take the center right away?}) 3. g3? {White does not even contest the center, and allows black to own the center for free.} d5 4. d4 cxd4 5. Nxd4 (5. Qxd4 Nc6 6. Qa4 {Was better, trying to prevent the huge center by black.}) 5... e5 6. Nf3 Nc6 7. Bg5 e4? (7... d4! 8. Bxf6 (8. Ne4 Nxe4!! {A common idea, and the main point, however, I have only ever seen white get to play it.} 9. Bxd8 Bb4+ 10. c3 dxc3 11. a3 c2+ 12. axb4 cxd1=Q+ 13. Rxd1 Nxd8-+) 8... gxf6 {and the N has no good square since Ne4 f5 is nice. Black will have the two Bs, the open g-file for the Rh8, and pressure down the c-file.}) 8. Nd4 h6? {Even if the tactics supported h6, losing the tempo is not worth it.} (8... Be7) 9. Bxf6 Qxf6 10. Nxc6?? {Horrible. This just strengthens the black center, and gives him strong b-file play soon. Also, because of Bf6 the move before, black also has the B pair.} bxc6-+ 11. e3? {Weakens the light squares, and gives black the time to win almost immediately.} (11. Bg2 {Developing, while not weakening the light squares, and it indirectly stops d4 since e4 hangs.}) 11... Bb4? (11... Rb8 {This just wins b2 while putting the Rb8 on a strong square. b2 is indefensible.} 12. Rb1 (12. Qc1 Ba3! {Although the easier-to-see Bb4 is also crushing.} 13. Nd1 Rxb2) 12... Rxb2! 13. Rxb2 Qxc3+ 14. Qd2 Qxb2-+) 12. Qd2 O-O 13. a3 Bxc3? {You have pressure, and two Bs in an open position, so giving them up so easily just to double his pawns is impatient.} (13... Bd6 {Idea Be5 and Rb8. Also white cannot develop his k-side. If Bg2, then Ba6 is annoying, or if Be2, Bh3. The weakening of 11.e3 is felt.}) 14. bxc3? (14. Qxc3 {If white is going to defend this miserable position, one of the key reasons is the strong black Q, so it makes sense to trade it off...or at least attempt to. If nothing else, after Qf3, it would be much better than the game.}) 14... Qf3 15. Rg1 Rb8 16. Be2 Qf6 17. Kf1? {One-move analysis.} Bh3+ 18. Ke1 Rb2?! {A good positional move, for sure, but it allows counterplay with g4 threatening Rg3.} (18... Qe5 {Stopping g4 due to Qh2, and centralizing the Q even move.}) 19. a4 Rfb8 20. Rc1 Rb1! {In many positions, you sometimes need to trade off your active piece, in order to be able to get at a weakness since it also removes a key defender.} 21. Kd1? Qxf2 22. Qe1 Qxe3 23. Bh5 Rxc1# 0-1