She says she feels a lot of times like she is just looking down at herself and watching herself lose control even when there is nothing setting her off or stressing her out. She says she hates that she does it and she knows that no one can stand to be around her because she can't even stand to be around herself. She says she has no idea why she does it because there's not usually anything bothering her when she does it, it just happens.
My daughter who is now 25 has Borderline Personality Disorder, which is only somewhat controlled by a cocktail of anti-depressants. She sounds a lot like your gf. My daughter however, has been in and out of hospitals and psych wards almost more often than I can count in the past 8 or so years. She abuses drugs and alcohol, and engages in self harm. She has suffered from bulemia, and one of her early hospitalizations was for that. She lost her driver's license years ago for drunk driving. She is impulsive and full of rage at the drop of a hat. She steals from loved ones, she lies and manipulates everyone she can. She has attempted suicide more than once. She is an extremely intense person. I have had to cut ties with her because all she wants is for me to give her money for drugs.
We have often called her disease a "monster" in her head, because she has a very warm loving funny side, and is talented artistically and musically, smart and a fast learner. But she has been unable to complete even a 2 year college and can't hold a job for more than a few months at a time. She is also very pretty. sigh...
She has gotten on disability payments from the government. Even that was difficult because for years she was virtually homeless, bopping around from one psych ward to sober home to crashing at a friend's, and you need a stable address to get on medical aid!
Your gf sounds difficult but not as severely affected as my daughter. Her rages and impulsivity and lies and disappearances, however, ring a bell.
Symptoms of BPD
Borderline personality disorder is a mental disorder that results in four groups of symptoms:
Impaired Emotional Control: excessive, poorly regulated emotional responses, especially anger, that change rapidly;
Harmful Impulsivity: impulsive behaviors that are harmful to you or to others, such as spending sprees, excessive use of alcohol or drugs, self-injurious acts (e.g., cutting), physically aggressive acts and sexual indiscretions;
Impaired Perceptions and Reasoning: suspiciousness, misperceptions, an unstable self-image, a poor sense of your identity, and difficulty in reasoning under stress; and
Disrupted Relationships: tumultuous relationships with a person close to you that vary from extreme fear of abandonment to episodes of excessive anger and the desire to get away from that person.
See if a test like this sounds like your gf.
There are other online tests as well.
If it sounds right, get a hold of a copy of the book Stop Walking on Eggshells for information on how to deal with a Borderline person in your life. This book has helped me and my ex and his gf learn more about our daughter, what it's like in her head, and how to cope. I recommended it to a friend whose SIL also seems to be Borderline and she also thought it was great.