Did she happen to just lay some eggs not long ago? If she was on the small side beforehand, that could account for the low weight. Otherwise, I agree with what Jerry said.
I'd only offer food once a week, and leave her completely alone otherwise. No peeking. No handling. She doesn't eat? Another week with no pestering. It usually doesn't take more than a few weeks for them to decide to eat.
Soft furs aren't a sure bet, so I'd save your cash unless you can find one locally to try out. I had a big name breeder pawn off a mouser on me recently without telling me up front, and she refuses anything but live small mice. Won't even *look* at a soft fur.
And speaking of, I wish folks would quit spewing that BS about snakes getting hooked on asf. If that's all you feed the darn thing, then sure it'll probably prefer those. But I've fed hundreds of snakes soft furs and regular rats, whatever I happen to have the most of at that time, and none has ever shown a preference. They eat anything and everything I offer.
Well, except this mouser.
Good luck!