Has anyone not been able to stop losing?

 I feel strongly that because you are not eating any animal protein, and because right now your protein needs are so high, that you REALLY need to work on getting in more than 90 grams of protein a day.     Most of us seem to need more than that.  Try to work on getting 125-150.   Really.  Trust me on this one.   I don't want to be reading a post of yours in six months telling us that you are in protein malnutrition.

If you are a size zero and can not eat protein you need to be in a hospital. Get the help you need now while you can still advocate for yourself. Karen

What scares me the most about what you said is this: at a size 0 you still feel as though you look fat.

Could there be a psychological component influencing or compounding the medical issues?

I second what Kirmy and Julie said--you need lots more protein.  All that other stuff is just filler and should be eaten last.  Lisa