14 combinations and 0-2

I solved 14 combinations (1-14) in 14 minutes from the 1001 combinations book from Fred Reinfeld, then I played 2 games in 10 minutes and lost both of them. The first was a queen pawn opening where he played early a4 and I made a mistake in the development, I really need to check that opening. In the 2nd game, I sacrificed a knight and then an exchange, but I forgot a defend against the checkmate. I needed to come back with the knight to e4 and push up the g- and h-pawns instead.

Current rating is 2496 after 4 games, overall result is 1-3.