Basically your loss is down to tactics. As I'm sure you have already noticed, instead of 9... Nxf6? better is 9... Qxf6 and instead of 18... Qd2? you absolutely must play 18... Qxf3.
Personally I find it difficult to give any good advice after 9... Nxf6? as objectively black is lost given proper play by white. Black should have something better instead of 16... Qf4?! and instead of 17... g5?! you could try 17... Bxe5 18. Rxe5 Qxf3 19. gxf3 to see if white can win this ending.The reasoning in your comments to blacks 14... Rfe8 is wrong. White's rook stands better on the e-file than blacks because e-file is open for white ie. your rooks vision is blocked by your own e6-pawn. Rooks are usually best placed on the open files so that in mind you could consider 14... Rfc8!? because altough c-file is currently closed you can open it by playing cxd4 at suitable moment.
In general you play opening quite well. At move 7 black could apparently win a pawn by 7... dxe4 8. dxe4 Qb6! (unpinning the knight) when white can't defend both b2 and e4. Also, it would be very interesting to know what you had planned against 3. e5 or 4. e5.
