My mom doesn’t want me to be with my boyfriend

I’m 16 and I’ve been with the same guy since the beginning of 8th grade, I’m a junior in High school now. My boyfriend just turned 18 this year. He is my whole heart, we have gone through hell and back and recently things have been getting better us, so I asked my mom for permission to let me see him and she’s given it to me, but she makes me swear up and down that we won’t have sex, and I hate lying to her because we do. We have multiple times and we’re always careful and it’s always consensual and something we both want to do and i don’t regret it. The only thing that makes me feel so uncomfortable is knowing I have to lie to her because every time she’s suspected it I’ve denied it and she doesn’t believe me at all and tells me she doesn’t want me to see him and basically tells me I’d be considered a hoe if we had sex even when he’s the only person I’ve ever done anything with. She makes me feel guilty and tells me he only wants me for sex and it makes me feel terrible. My mom and I just had a fight today because she’s convinced we have sex and I had to deny it in every way possible because she would never forgive me. I wish she’d understand it’s natural and we’re careful and I feel comfortable because I would love to be able to tell her but even the thought of me doing something makes her not even wanna look at me and now that she suspects we’ve done things she’s forbidding me from seeing him and I don’t know what to do. He’s been my boyfriend for such a long time and I love him. I feel so terrible, she makes me feel like a bad person for it.