Just so you are aware, if your setup is correct, your snake shouldn't fast through the winter. Breeding males might fast for a few months bcause their mind is set on other things, but a baby shouldn't fast.

I would just stick with one medium adult mouse until the snake reaches 300g or so, then you can try bigger mice or two medium mice per week. They don't need to be stuffed full, and if they get stuffed, they will fast to catch up.

All of mine, with the exception of Amani(who is a turd), ate throughout the winter, even the males.

As they age, their metabolism slows even further, so this is why a 3000g female doesn't need a jumbo sized rat. They grow just as well on smaller meals fed more frequently.