How do I tell my mom I'm only 17..

Brooke
I'm 5 weeks right now I turn 18 in a few weeks I was gonna wait to tell her after I turn 18 in case she tries to kick me out or force me to do something I don't want to do . I also wanted to wait till I was 8-12 weeks because I don't want to tell her and miscarry . How and when should I tell her ?