Is she still seeing the counselor still and/or psychiatrist (the medical doctor you spoke of would probably be a psychiatrist, he would have been the one prescribing the antidepressants. That she was taken off them could indicate that she is bipolar as antidepressants can cause people with bipolar disease to "cycle" (between the depression and the mania/her strange, angry outbursts) faster).

If she is bipolar, she's not likely to get much better without some help from therapy and medicine. It sounds like her problems are not something she can fix by herself with time and getting away or finding (either one :-) herself. I would tell your mutual friends to see if they can get her back to a therapist and psychiatrist. I don't think you'll see a whole lot of change in her if she doesn't get some help and I don't know that you'll want to be in a relationship with her if she doesn't get some help and stabilize some?