Sometimes he will eat 2 or 3 adult mice, I usually offer him whatever he will take. A lot of the time he will only eat one though, and skips a week once in a while. He has been a lot better about eating regularly as he is getting older, though.
He also seems to go off eating for 2-3 weeks either side of a shed, so every time he sheds he doesn't eat for 4 weeks or more.
Welcome to the world of owning ball pythons! They can be a real PITA sometimes!
Pics would help greatly. It sounds like he is a little light, but without pics that is just speculation.