She doesn't need to eat weekly. That's a ton of food for an adult. A medium once every 2 or even 3 weeks would do her well. Given that she was fed 2 mice once a month before I'd definitely wait until next year to breed her and only feed weekly around breeding time so she can save up for the whole egg process, but weekly is too much for an adult to eat regularly. One of the main reasons BPs go off food, is because they're given too much. She likely won't grow longer, at least not much, and weight doesn't matter much. Age and body condition do. At 5 years, as long as she has great body condition she'll be fine