It's pretty usual for ball pythons to stop eating or not eat as often as you would like. We weigh our snakes every feeding, Wednesday/Thursday but that is a tad bit obsessive. As long as she isn't loosing a substantial amount of weight and looks good she should be fine. Double check your temps, humidity and her behavior. If all that pans out you should be good.

We have a small female python now who will only eat live mice and only every other week. All the other snakes eat happily once a week but she isn't interested. She doesn't act hungry and loves her warm side. She apparently is watching her figure lol