@HungryHazelEyes I think you seriously need to request a second opinion it took me a couple of years to get my full diagnosis, and there was a lot of in depth reports. I been known to psychiatric services since I was 15 yet didn't get my bipolar diagnosis until roughly age 22, and I was even older getting the schizophrenia added. I had had in total over two years of therapy including psychotherapy and ACAT.
It is common to have a full blood works done before diagnosis it's not that low vitamin levels cause schizophrenia or bipolar, it's that certain vitamin deficiencies can cause symtoms which mirror mental illnesses, once the vitamin deficiency is addressed the mental health symptoms clear up. But in my case and many others a person with severe mental illness may have severe vitamin deficiencies as a result of self neglect. But in those cases once the vitamin deficiencies are cleared up the symptoms remain.
I don't know the procedure where you are but here only a psychiatrist can diagnose you, a therapist can make suggestions but then a psychiatrist has the final decision.
Groups of friends don't influence me or my schizophrenia I am always the same there are people I'm more comfy with who I can be myself with meaning I'm less anxious and less closed, but I'm always the same.
Schizophrenia medication is hard to tolerate I wouldn't take it lightly ask for a second opinion first as I imagine it would be even harder on a developing body to tolerate strong psychiatric medications. If she does need these medications it will be less harmful for her to take them as going unmedicated is very damaging not just mentally but usually physically from self neglect, self harming, and with schizophrenia there is just the general lack of understanding how to care for yourself. So if she has schizophrenia then by all means the meds are the way to go but you don't want her taking them without a really good investigation I hth, I feel kinda useless tbh but I've tried my best.