The pill

I recently went to a doctor to get on the pill and the appointment was fine but the doctor didn’t ask me many questions and he didn’t ask if i am sexually active. I’m 17 and I haven’t started the pill yet because i was told to wait until i get my period to start it but i’m due in 5 days. Does being sexually active affect being on the pill because i’m scared he assumed i’m not sexually active and that it will affect my cycle once i’m on the pill and how well the pill works as a contraceptive. I can’t ask my mum this question because she doesn’t know I’m sexually active.