help me

my mom said she was gonna take me to the doctor to see if "i have had sex, or any penetration down there" and i have had sex before but i want to know if the doctor can tell or how she will be able to tell or what can i do to make it seem like i have not. i've been told that the doctor can not share with my mom if i have been havin sex without my permission. but if i say no don't share it with my mom . my mom will know that i have something to hide and how do i break it down to my mom or simply covering it up . cause she doesn't let me use tampons either so maybe i could say i have ?