Then I would tell you that she will grow as big and as fast as she is genetically determined. If you want an obese Ball Python that will not live long and will die from fatty liver disease, then go ahead and power feed her.

Feed her an appropriate meal(adult mouse) every 5-7 days. When she gets around 350-400g, try two mice.

They are not meant to be overloaded with a ton of food, or they will stop eating. Feed regular small meals and she will reward you will rapid growth. Even adult females don't need anymore than 65-70g of food per week to grow and maintain their body weight. You can feed them more, but they will just process it as waste(ie poop), and you've just wasted your money on a huge rat that she didn't even use 1/4 of.