My mom keeps trying to stop me from having sex. How do I get around her?

I'm 18 and my boyfriend is 17. We have been dating for 4 years now and we're ready to have sex with each other. I told my mom that I wanted to go to his apartment on the weekend and she was like uh uh no way and if you go and I found out you're grounded. But I'm literally an adult. 🙄 I told my boyfriend this and he told me that I can just ask to go to a friend's house or go to the movies and then once she drops me off he can come pick me up or we can get in his car after school, he parks it someplace that's not usually visited, and we could do it there. Or we could cover up his windows. They all sound good but idk which one we'd go through with.

Update: You guys are so hypocritical on this app?? Like when moms post about their teens having sex you guys freak out on them but when I post about my mom being overbearing then you guys go off on me. Anyways, I told my mom I was going to the movies then my boyfriend picked me up and we had sex. But thank you guys for the advice because now I will be moving in with my boy and I expect myself to fully be out by the end of next week. 👌