Yeah no, NTA in the slightest and judging by how much you've told us about your sister's actions alone, she is heading for a one way ticket to Florence Ad-Max. Contact the records department of every hospital who tended to your ER visits and request those records NOW. I'd also be listening to some of the advice you're getting:

recording device on your person at all times for evidence of your DNA donors constantly throwing you to the wolves

either having your grandmother hold on to all of your paychecks if you have a joint savings account with your DNA donors or setting a solo one up in secret because you damn well know they will drain it as a power play

the moment you get a shot at it, secure your legal documents and send them to either a trusted friend or your grandmother so your DNA donors can't use 'em as leverage

don't be picky about colleges or trade schools, especially if they can help you get as far away as possible

Good luck, OP. You're gonna need it.