Multiple Personality Disorder (MPD) is now called Dissociative Identity Disorder (DID) and it is only one diagnosis within a category of Dissociative Disorders, which all have to do with disturbances of identity, consciousness, memory, perception and behavior. Though you say you don’t have amnesia, you do say that you don’t remember the abuse you suffered as a child. Depending on how young you were when you were abused it sounds like you may have memory issues about the abuse, which could still fit with Dissociative Disorders, in addition to the personality changes that you describe. And just because you can change between the personalities at will, does not mean you don’t have issues with dissociation. Many dissociative clients describe being able to speak to themselves inside their head, so again, this isn’t an unusual symptom.
However, dissociation is also a part of Posttraumatic Stress Disorder (PTSD) which is related to having suffered a trauma (or many traumas). Furthermore, our mind can be very creative in coming up with ways to cope with bad situations. You may have learned to have two different parts of yourself just as a means of coping with stressful situations and you still do this out of habit.
Working with a professionally trained therapist is the only way to really know what the appropriate diagnosis is and how best to address the problems in your current life. Whether you have a creative way of dealing with stress or you really are having dissociative symptoms, I recommend speaking with a therapist soon.
All the best,
Dr. Holly Counts