going on the pill.. please help

i have an appointment to go on the pill coming up and it's for my period but i've also started having sex... i'm cool telling my doctor this but i'm still a minor so my mom has to come with me. she doesn't know i'm not a virgin anymore. how do i have the appointment without her finding out i'm not a virgin anymore, because i can't lie to my doctor and say i'm not sexually active!? please help