This is very ableist of your sister. Nobody knows what it’s like for you except you. She might know some general information, but you’re the one with the personal experience, and she is far from an expert if she is still in school (and she won’t be one when she’s finished, either; people who are recognized as experts in this kind of field have doctorates and have spent years specializing in particular disorders - this is totally disregarding the fact that the true experts on what it’s like to have a disorder are those how actually have the disorder in question).
Is there something that you would be willing to hear about from your sister? Maybe she can recommend articles or books that she’s read for her classes. This will keep her involved and let her feel like she’s helping.
But what you really need to do is make it clear to her that you have a doctor/psychiatrist/therapist (whatever) and she is not them, so she actually has zero say in what treatment you pursue, and she definitely doesn’t know anything about your particular case since she is not on your treatment team. In fact, it is unethical of her to try to be a part of your treatment because she is both family and still in training. When she tries to correct you about one of your disorders, tell her “that doesn’t apply to me and my treatment, and I am not talking about this with you.” You have to set and assert your boundaries here.
Followers, what do you recommend?