Problems with the middlegame

I just finished a game with KJFoster. I lost of course, and this is the 4th time we've played. I did much better in using my time. He noted that I do fairly well till around move 15, then I kind of fall apart.

crok has looked at some of my games and noted some issues I have. He is  right about my quick play and exchanges. Now some, I just missed, never saw it, so not deliberate. I notice I don't have a lot of patience and I tend to like to attack. I've also noticed when I do a computer analysis of my games later, I often don't exchange when I really should. So it's half and half, too much capturing or too little.

Here's the game with KJ Foster today. Did okay in the opening. I seem to fall apart switching from opening to middlegame.