Please review my game in the King's Gambit Accepted In the following game I played as White where I was mated. Can you comment on my game and how to improve?

I'm particularly interested in understanding the my opponent's mating attack.

[FEN ""]
[Event "Live Chess"]
[Site "Chess.com"]
[Date "2016.05.26"]
[White "anandsadasivam"]
[Black "PMajstor"]
[Result "0-1"]
[WhiteElo "878"]
[BlackElo "886"]
[TimeControl "10|0"]
[Termination "PMajstor won by checkmate"]

1.e4 e5 2.f4 exf4 3.Qg4 Bd6 4.d4 f6 5.c4 Nh6 6.Qf3 b6 7.a4 a5 8.h4 O-O 9.Bxf4 Bxf4 10.Qxf4 d6
 11.g4 Nxg4 12.Ne2 h6 13.Bh3 f5 14.Rf1 Qxh4+ 15.Ng3 Qxh3 16.Nxf5 Bxf5 17.exf5 Ne3 18.b3 Nc2+ 19.Kd1 Nxa1 20.Kc1 Rxf5
 21.Qxf5 Nxb3+ 22.Kd1 Qxf5 23.Rxf5 Nxd4 24.Rf4 Nbc6 25.Nc3 Rf8 26.Re4 Nf3 27.Nd5 Ng5 28.Rg4 Rf1+ 29.Ke2 Rf8 30.Nxc7 Ne5
 31.Rd4 Rd8 32.Nd5 Nc6 33.Rf4 Re8+ 34.Kd3 Ne5+ 35.Kc3 Ng6 36.Rf1 Ne4+ 37.Kd4 Nd2 38.Rd1 Nf3+ 39.Kc3 Nge5 40.Nxb6 Rb8
 41.Rxd6 Ng5 42.Nd7 Ne4+ 43.Kd4 Nxd6 44.Nxb8 Nexc4 45.Nc6 g5 46.Kd3 g4 47.Ke2 g3 48.Kf1 h5 49.Kg2 h4 50.Kh3 Nf5
 51.Nd8 Nb2 52.Nc6 Nc4 53.Nd8 Kf8 54.Ne6+ Ke7 55.Ng7 Nxg7 56.Kxh4 g2 57.Kh3 g1=Q 58.Kh4 Ne6 59.Kh5 Kf6 60.Kh6 Qh1#
 0-1
I think your first step toward improvement has to be: don't just lose material. 11.g4 is the first example I see. There seems no rhyme nor reason for just letting the opponent have that pawn. Next is 14.Rf1. There seem to be reasonable ways to not lose the h4 pawn. And finally 15.Ng3 dropping a whole piece on h3, when 15.Bg2 would have saved it. Why keep material? 1) More material for you means you have more material to launch attacks, and 2) More material also gives you more defenses for your king if your opponent goes on a premature king attack.