I’m 18 and now that school is starting my mom won’t let me work in the afternoons

I was working in the morning because it was summer break and I didn’t have school. But now that school is starting again they scheduled me on the afternoons and she’s mad that they schedule me at 5 pm to 10 pm. She told me she’s not going to take me. And literally my step dad screamed at me you’re not going to work in the afternoons. I hate that they’re treating me like a little girl when I’m 18 years old. It also sucks that I don’t know how to drive or have a car yet.