This is a French exchange variation. Look at the position after 12 moves. Your bishops are pointing at the kingside, and you can start an attack with qh5, forcing some weakening of the kingside. I see ways to continue no matter which defensive option black choses. Instead, you decide to spend two moves trading your developed attacking light square bishop for his undeveloped light square bishop. Bad plan.
I might have time for some other comments later, but this mistake contains a definite lesson.
Please let me know if this is a reasonably good live game by me. I am white. I think it is some sort of French defense. I guess it's pretty sloppy but I don't really know much about opening books.
thanks