"shrink", in my world, usually means a psychiatrist.
T means therapist.....who isn't a psychiatrist. has a psychology degree, social worker degree, etc. i'm a T and i can't prescribe any meds.
PCP (primary care physician) can be a general practioner, an internist, a family practice physician, etc. and they can all prescribe psych meds. i don't think they should, but "oh, well".......

although my first AD was prescribed by an internist that i trusted very much. it just scares me that so many primary care physicians are so poorly trained when it comes to psych meds.
we had a pediatrician who would send every kid home from ER with a prescription for ritalin. we called him Dr. Ritalin. i don't think that each and every kid that came to ER had attention deficit disorder.
a psychiatric nurse is highly trained and can prescribe psych meds.
hope you aren't too confused now......xoxoxo pat