“I think your parents will probably need to fill out the FAFSA for you to get aid anywhere.” Nothing can make them.
“if someone can afford to save for a child’s college but chooses not to and fritters the money away instead, that makes them a bad parent.” We don’t know enough. We don’t know they’re truly frittering or why the brother is in private school. Just saying.
If there is a crisis, yes, OP needs to ensure this is reported in the right ways. If needed, CPS can get copies of a birth cert and SS card. But we don’t know why a therapist, nor why this wasn’t reported.
OP did start with complaints about their spending, the original point was not having money for herself or saved for her education. If there’s more to this story, we really don’t know.