If you're feeding every seven days, I think you're probably fine. My female BP is 2 years old, a little over 3' long, and around 1000g in weight....and she is currently getting only TWO small mice every seven days. And she's gaining weight at a reasonable and healthy pace.

EDIT: One more thought....BP's are naturally heavy bodied snakes (compared to say...a corn snake)....but they do not have to be "Fat."