am i in the wrong?

i’ve posted about this before but i feel like i need a bit more advice. but i’m 18 years old and currently in a 6 month relationship. but my mum keeps asking me invasive questions and asking me to tell her when we’ve slept together. she’s mentioned it a few times but yesterday we had a proper conversation about it, where i told her i did not feel comfortable talking to her about whether or not we’ve slept together or not. but she kept saying i HAD to tell her. i’ve already slept with my boyfriend and we use condoms. i told her that when i do start i will be safe but she said i still have to tell her. i don’t feel like it’s her business to know. she also asks me if we’ve done anything everytime i leave him. we could go to the park and she’d say oh did you kiss. i came back from his house yesterday and she said did you have a kiss and a cuddle, which i said yeah and she said my name and made a comment in which i just said i am 18. what else can i say to her so she stops invading my privacy? it makes me feel so uncomfortable especially when she’s going to have to see my boyfriend knowing the stuff we’ve done.