The biggest rat a ball python female will ever need is a medium. If she is not going to be bred, I would monitor her weight carefully and attempt to back her off to once every two weeks. If her attitude becomes negative or she is not making small gains in weight I would then return to the weekly schedule. If she continues to pound mediums like she is currently doing she will most likely at some point go into a prolonged fast. This doesn't bother me but it seems to drive a lot of people nuts when their animal doesn't eat when they want it to.