Gyno?

Im going to the gyno tomorrow to get a lump checked out in my boob. The thing is, I'm 18 and I have never been before so I'm scared they'll check me out down below and will be able to tell I'm not a virgin. My mom is close friends with the doctor I'll be seeing and she'll kill me if she finds out and she'll never let me see my boyfriend again. Can they tell if you've had sex before?