18 years old but still a baby

So its time for graduation and all that. My mom is like its time to do your check before college well..that's fine and all except she doesn't know i have sex every weekend or two. Im not sure how to go about my doctors appointment. She thinks im a virgin still and she wants me to stay like thay till a bit after i leave..should i lie to the doctor or tell her not to come...idk what to do honestly..i dont want her to find out yet..