Need help/advice

So I’m 18 about to start college and about to move out into an apartment with my bf. I live with my mom and step dad currently. Nobody knows that I’m about to move out.

I’m gonna buy my bfs friends car so I have one, but I’m afraid my mom isn’t gonna let me move out when she finds out.... even if she does let me go, I’m afraid she isn’t gonna let me take anything (phone, clothes, my bed, ANYTHING)...

I’m just scared and worried and nervous so I’d like some kind of advice.