I’m 18 and my mom doesn’t want me to have sex

hi so me and this guy are kinda dating, I want to have consensual sex with him and I told my mom about him and how I like him but she keeps telling me that she would be very disappointed if I had sex with him and stuff like that. I really want to have sex with him obviously protected sex but now she makes me feel guilty and I’m an adult but now I guess I have to listen to her what should I do? I’m also 18 not sure if that young..but