Questions on gynos

So Monday I had my first gyno visit. It went well, it was just basic questions. One thing that they asked is if I have sex and my mom was in the room so I said no. Today I went back with my best friend to tell a nurse that yes, I do. But I don't want my mom knowing (for when they look at me down there in the future.) when I went, I asked a receptionist if I could talk to a nurse or my doctor if I could change part of my medical history. She said it would be free but they were short of staff but she said she could write it down and put it in my file. When I told her what it was about, she obviously seemed a little awkward or uncomfortable. Will she tell me mom, or will a nurse or doctor? She said she'd write it down that anything like that would be confidential and she would write and explain that I want it just between me and the facility there. But I'm scared. She seemed uncomfortable and i made it known I had a boyfriend (so it's not like just going around and that I wasn't being abused by some older guy.) but I'm scared she'll call my mom, or that the doctor will tell me my mom (they occasionally work at the local hospital together, but she's a nurse and works at a different part so it's not like they're super close.). What should I do? I felt like I was doing the right thing by being honest about what I've done because the office needs to know in case something comes up, but now I'm scared she or the doctor will tell my parents. I'm 18, he's 20. I'm almost 19..
​Do you think they'll call or tell them?