As pp have said. There are actually other things to be more afraid of than your teenager having sex.
I had wonderful parents, truly I did/do. They did everything they were supposed to do and kept strict watch over my curfews. The only thing we could never discuss with eachother was sex. They were squeamish about it, I afraid of their disaproval. But they didn't worry, because I was a geek, a bookish nerd. Not the stereotypical loose teenage girls with a bad set of morals (I seriously doubt that this is even a typical representation of reality).
Yet I did get pregnant at 15. Not through ignorance, I knew about contraceptives and my rights to obtain them. But I was a teenager, I was embarrased to talk to my parents (who would have cut me off from my boyfriend), afraid someone would see me at the GPs and quite frankly, stupid enough to let my impulses rule me good common sense to wear protection.
It didn't end my life, didn't ruin my choices. My parents were wonderfully supportive and have never shied from any subject with me again. My DS is 8 now and a wonderful child. I went on to have my DD (same partner) at 21 and though we are no longer together (split up after 7 years together), I get on wonderfully with my ex even now. And funnily enough, I don't regret having sex young - simply because I was in love and we had many happy years together afterward.
I have a career to be proud of and have a lovely life that I am very happy with.
^^ btw, this is not a promotion for 'underage sex is fine!' but rather pointing out that it is of course worthwhile to be understanding of your children, to accept their choices and help them to avoid the major repercussions that could occur (such as pregnancy, STIs etc). When you can't do that or the teenager in question cannot for whatever reason safely talk to his/her parents, then I for one am extremely glad that they have the right to access contraception in privacy.
So OP, YABVVVVU.