Sandi, I've always heard 6 months of documented sobriety in AA, but that is for an alcoholic. I don't think any such requirement would be made of BU--but she should not drink again for the health of her liver and for possible transplant evaluation at some point. I wouldn't even consider her a social drinker--more like a light drinker.
I have AIH but I take Ursodiol since I was having a little cholestasis from my azathioprine. I'm assuming you're on Urso for your PSC? Do you already have cirrhosis from the disease or have you only had the strictures? I also read that most PSC patients end up having a transplant. You really should check with your doctor on when they do evaluations for that or how advanced the disease needs to be to be on the list.
Please let us know how you're feeling,