I would stop feeding her in a separate container, it is a myth that feeding a BP in its cage will make it aggressive, and you only increase your chances of getting bit feeding in a separate container.
For young BP's you can use the 15% rule to get an idea of how much rodent your snake should eat every week. Simply multiply the weight of your BP (in grams) by 0.15
So a 100 gram snake should eat about 15 grams of rodent. (100 grams x 0.15 = 15 grams)