Advice on psychiatry, what field is this considered ?

I am very interested in psychiatry. I want to do behavior analyst. And diagnose people with thief right mental disorder. I do not want to deal with any medication (if I do not have too). Maybe right a few prescriptions sometimes if needed.. I am wanting to do things with the patient like writing, drawings, pictures, exercises, etc. After the analysis.. Can you tell me what field this is ? Am I right about it being psychiatry and not physiotherapy or something else? What should I major and minor in? I want to know a lot about the brain! By the way I am 15 please do not judge. Thank you for taking your time to answer!