Transition from Attack to Defense

Recently I played a corresponding game at chess.com. It is one of the games I played in a Ruy Lopez thematic tournament. I attacked first, but later on have to defense and lost the game quickly (as I thought). Below is the PGN and an embedded PDF analyzing the game.

[Event "Ruy Lopez - Round 1"]
[Site "Chess.com"]
[Date "2011.07.25"]
[White "nadreck"]
[Black "whily"]
[Result "1-0"]
[WhiteElo "2022"]
[BlackElo "1882"]
[TimeControl "1 in 5 days"]
[Termination "nadreck won by resignation"]

1.e4 e5 2.Nf3 Nc6 3.Bb5 {Thematic Game - This is the starting
position.}  Nf6 4.O-O Nxe4 5.Re1 Nd6 6.Bxc6 dxc6 7.Nxe5 Be7 8.d4 Be6
9.Bf4 O-O 10.c3 Nf5 11.Nd2 c5 12.g4 Nh4 13.dxc5 Bxc5 14.Ne4 Bd6
15.Nxd6 cxd6 16.Nd3 Qd7 17.f3 Qc6 18.Re3 Bxg4 19.Nb4 Nxf3+ 20.Kh1 Qd7
21.Rxf3 Bxf3+ 22.Qxf3 Rfe8 23.Rg1 Re6 24.Nd5 Rae8 25.Qg4 1-0