Yeah, the thing is that there's a LOT to study in psychology school. In the USA a Master's Degree in Psychology does NOT require a course in trauma and it's impact on mental health. Unless they do their own research and pursue the training and education related to dissociative trauma the most many get is just a paragraph on DID.

That being said I have 2 things I could recommend that might help you feel more at ease with your experience regardless of the diagnosis.

Eleanor Longden's TED Talk on 'hearing voices' available on youtube - whether the chatter is psychosis or dissociative parts, I find she has helpful advice.
The Body Keeps The Score by Bessel Van der Kolk, available in paper-back, and 8hrs of audio book on youtube as well - This book focuses on how trauma impacts the body and mind and goes very deep on it and includes information about the benefits and drawbacks of various treatments.