I would think the vet should have known that if you waited to go to the specialist that the break would be too old to repair. So he said he souldn't fix it ...what options are you being given? I certainly wouldn't just leave him without the cast as if nothing else I would think that would leave him in a lot of pain. You said suggesstions besides finding another vet but at this point I don't see any other option but to find another vet. Doesn't seem like you are being given any proper options with the vet and specialist you have already talked to.
Poor baby, my thoughts and prayers for her healing.