Your the only one who can get you out of a rut. One step at a time. Focus on getting your mental health under control. Get to a psychiatrist be evaluated, treated, and than the world will start to open up. Next get a Ged or a job, whichever strikes your fancy. Than you can worry about a car, but medical transport can take you to appointments and some services provide transportation to work. You are not your sisters. I am not my brother. Do the best you can do. Strive for a better life for yourself.

Oh and start applying to subsidized housing or disabled housing. You should be on disability if not apply to SSD. But to apply you need to be working with a doctor. So get to a doctor.