My 24 inch BP takes two fuzzies every five to seven days and is nice and plump, and has added four inches since I got her. She is shedding every four or five weeks. Generally you should feed a prey item equal to the maximum diameter of the snake. I started with smaller prey items, because my snake was thin when I got her. Her previous owner didn't have husbandry correct so she wasn't eating. A single fuzzy is actually too small for her, so I am doubling up. I will be switching to larger mice as soon as my last few fuzzies run out.
Considering the food requirements and minimal energy expended by a ball python, a single large mouse should be sufficient if it is given every five days. Perhaps there is something else keeping her from gaining weight. How long has it been since the hunger strike ended?
David