Get a weight ASAP. Also, the rat should not be bigger than the thickest part of her body. There should not be a noticeable lump after she eats.

Refer to chart below for proper size. I believe as a BP matures, you can spread out feeding intervals from weekly to bi-weekly, or longer, but you are a long way off from that if a small rat was big. My adult BP - about 1,800G, eats a medium rat every two weeks. When fed weekly, she would often refuse. She fasts in the winter and loses some weight and then gains it all back within a few months of returning to food in the spring, even on a bi-weekly feeding schedule.