It is tough to say since none of us are psychiatrists. How many psychiatrists have seen your sister? Diagnosis with so many symptoms can be tough especially as it is not uncommon to have more than 1 psych disorder going on. And a lot of psych symptoms can manifest in different psych diagnoses. I agree, finding the correct mental health professionals to help is important. Also, seeing them consistently as a psychiatrist may change diagnoses or add to them if they see or hear about symptoms not mentioned earlier.
My guess is that she may have more than 1 thing going on, but it’s only a guess.

It may or may not have help, but has your sister had complete blood work done, checking hormones, vitamins, minerals? Something could be off there. Not saying that could be the whole problem since it sounds like she has a lot going on, but having things off on the blood work doesn’t help?

Could she be doing drugs as well? That could compound things.

Best of luck. It sounds like you are a very good sister. Don’t give up on finding answers though I agree with the previous poster suggesting with your dad or you retaining guardianship of her because her behavior sounds very erratic.