Was there any mistake in the opening?
3 Bc4 is questionable. Black can take 3...Nxe4. 3 Nxe5 and 4 Nxe5 or 3 d4 are mainstream.
7 Qd3 is not as good as 7 Re1: the queen must not move too soon and it is Always good to put a rook on a file that may open.
11 a4 is no good you can just take 11 dxe5.