Although it's much easier to feed a larger BP rats(because you don't need as many), you can easily get your snake up to breeding size feeding mice. If you fed her 2 to 3 large adult mice a week she should be breeding size next year.

If you go to Pete Kahls facility on feeding day you'll notice that he has many large adult females that only eat live mice. Some are right next to siblings that eat rats, and they're around the same size.

In other words, if it works for Pete, there's really no need for you to worry about your snake eating mice.

BG has some, but he usually(not always) can get them to switch to rats. Pete just doesn't care(he does, but not much) and will feed mice if they want them.