You've received a lot of good advice, but you're going to have to evaluate how to confront your daughter based on what kind of relationship the two of you have & what her personality is like.
Having covered just about everything at least once with my three daughters that are now grown, I can tell you that as tough as this is, it can work out just fine between the two of you & potentially bring you closer.
If my girls felt they were old enough for anything, then they were old enough to know all of the responsibilities & consequences that came along with it.
Confrontation gets misused many times, but isn't always necessarily a negative thing. If your daughter is young enough that she's still on your insurance & you'd be the one covering any pregnancy or treatment costs, you have certain rights to know what's going on with her.
Teens seldom get the big picture, or see themselves as becoming a statistic. Having to look at the realities of what could happen & ultimately what it could cost in both emotions, as well as financially, can be an eye opener.
I was an unwed mom at 20 & raised my first daughter alone for 7 years, so I was very open with my girls about the blessings I received, as well as the heartaches that were a part of the consequences. Not just for me, but for my daughter too. She had to overcome being abandoned by a father that lived in the same town with her. That was something that created issues we had to walk through in her teens & her feelings of needing male approval.
Do let your daughter read some of these responses you've received if you feel she'll "hear" what's being said. I've never regretted my daughter, but I've wished so many times that I'd have made better choices regarding sex, for her sake more than my own. Having been married for many years now & knowing the value of truly being loved emotionally, I know that I never really had a fulfilling sexual relationship before my husband. It's hard to explain that to a teenager though.
Pray for wisdom & that God will give you both ears to hear & hearts that are willing to receive.