Did the vet do a stool sample? No internal or external parasites? If you're sure of her health & provenance & your husbandry is absolutely on the mark, I'd either offer live (mice, rats,...?) or sell/re-home her to someone that could offer her soft furs if they're okay taking on the challenge she seems to be. Was she a wild caught import animal or where did you get her? And how old is she?