These dreams have been persisting for a few months now and the eating problem only a few weeks. Oftentimes it is difficult to work through emotions on our own. She should consider seeing a therapist. No offense, but a therapist could probably help her more than you could. Don't be surprised if your fiance shrugs off the idea of seeing a professional.
Many people think that they can fix their problems on their own.
Try and convince her to at least give it a chance. If she truly wants to get better , then she will probably be receptive to the idea. I think it is very wise to hold off on the wedding until her problems are resolved. A guy that I really like keeps saying that we are just good friends, although we are intimate. I'd just like to have an intimate, monogamous relationship until both of us see if it will work.