Mate With Queen and Bishop

I recently played a game of speed chess at chess.com in which my queen and bishop combined to mate. My opponent was Onyx of the USA who played black. Here are the moves of the game along with my commentary:

1. e4 e6
2. d4 d6

Here d5 is the most popular move for black.

3.Nf3 Bb7
4.Nc3 Bb4
5.Bd3 Nf6
6.e5 Nd5
7.Bd2 Bxc3
8.Bxc3 Nxc3
9.bxc3 0-0
10.0-0 f6
11.Qe2 fxe
12.Nxe5 d6

I capture the e-pawn with my knight because the black bishop threatens to capture my knight and weaken the pawn shield around my king. Black has yet to develop the queen knight.

13.Qh5 Rf6

I ignore the attack on my knight. Black defends the f-hile with his rook but a better move is to capture my knight with dxe5.

14.Bxh7+ Kh8

Black makes a mistake. A better move is Kf8 because it gives the king more escape squares. With best play, though, I prevail because I have a winning position.

15.Ng6+ Rxg6

Black is forced to give up the rook.

16. Bxg6+ Kg8
17. Qh7+ Kf8
18. Qh8+ Ke7
19. Qg7#

My queen and bishop combine to mate the black king. My bishop prevents escape to e8 and my queen prevents escape to f8. Black loses because of his lack of development. His queen rook, queen knight and queen remain on their original squares.