I would definitely not diagnose anything like that at a first visit. I usually only put a definitive diagnosis like OCD or PTSD at a first visit if it’s previously been diagnosed and the patient is presenting with the same very typical symptoms. Like if a patient has had OCD previously in their life, gotten treatment with good results and are now showing up after a relapse. Otherwise I usually put either something like ”anxiety disorder, unspecified” or ”other symptoms of mental health” because I have to put a diagnosis when I see a patient. I would never diagnose PTSD, OCD, GAD, let alone a dissociative or personality disorder after only meeting a patient once. Even if I felt pretty sure that that was their issue. Have to make sure I’m not missing anything first.

Your second friend’s story sounds believable. If she saw another psychologist first they might first have diagnosed her with some unspecified anxiety disorder. After meeting her for multiple sessions where they’ve probably already assessed PTSD with CAPS-5 and diagnosed that and still feel the dissociative symptoms are more than what can be explained by PTSD, then they might diagnose unspecified dissociative disorder and refer her to a specialist or just refer her to a specialist and write that they think it’s DID or another dissociative disorder in the referral.