Jessika,
Deborah posed some excellent questions, and it seems by your answers that you have been keeping your ball python in a very well maintained enclosure for some time. I would bump your colad and warm side temps up about 2 degrees each, if possible. Lastly, I don't know what you call a medium rat, but I have some 3000 gram females that I may feed a medium rat to occasionally (mostly because a feeder did not get eaten for a few weeks, and got too big. Try feeding your guy some smaller rats, and I think he will eat more regularly. I believe Lawrence might have hit the nail on the head when he said, "It could be that you have been feeding her larger food items and she just needs to "catch up".