We keep detailed records of our snakes' body weight and the weight of each food item and when/how often fed. The "mistake" I made with my royal baby in the beginning was feeding him items more around the size of his tiny head than the middle of his body. So I kept feeding 3 or more small fuzzy/pinkies when he could have taken a much larger mouse or rat pup.
Since she's a female, she'll probably be better about eating in general than your male.
Try feeding once a week. If you have a food item that is about as big or a bit bigger than the fattest part of her body, feed one of those and wait 7 days before the next feeding. If you don't have that size, you can feed a few smaller sizes till you see a noticeable bulge. (In general because of the fur that is not digested, one food item has more nutritional value per gram than several small ones.) I've never had a problem with any of my snakes over-eating, but I suppose it can happen. Try to adjust the size and gradually increase over time. As Merlin said, they are opportunists and their bodies are not programmed to be fed the same size meal on a regular schedule, so you'll pretty much just have to figure out what works for your little girl.
Generally when I fed Monty 34 grams of rat pinkies, he'd put on about 10 grams of weight.
That has been our experience with growing baby pythons in general: about 1/3 of the weight of the food will be turned into body weight.
I hope that helps.
