Mated!

MANAGED to get mated in under 20 moves as White against a lower-graded player this morning in round four of the Bradford U171.
Spanton (167) - Charles Proctor (154)
Modern Defence
1.e4 g6 2.d4 Bg7 3.Nc3 d6 4.Nf3 a6 5.a4 c5?
Not in ChessBase's 2018 Mega database.
6.d5?
I rejected 6.dxc5 because of 6...Qa5, but White is much better after both 7.cxd6 and 7.Bd2.
6...Bg4 7.a5 Nd7 8.h3 Bxf3 9.Qxf3 Ne5 10.Qg3 Nf6 11.Be2 0-0 12.Be3

Despite missing the best continuation at move six, White is much better

12...b5!?
Whatever the soundness of this move, it does have the practical advantage of distracting White from his kingside build-up.
13.axb6 Qxb6 14.Ra2?
White is pleasantly better after the calm retreat 14.Bc1, which ends Black's queenside counterplay.
14...Qb4 15.f4??
Catastrophic. I somehow missed that my c3 knight is not protecting e4.
15...Nxe4 16.Qh2 Nxc3 17.Bd2 Nc4 18.Bxc4 Qxc4 19.Ra3?
I have given this a question mark, but it is arguably the best move in the position as it allows my opponent to immediately put me out of my agony.
19...Qe2#