I wold deal with this by telling her "MY HOUSE MY RULES".
If she persists and becomes stubborn, I would tell her to go live with these guys then and let them provide for her. She will have to learn the hard way, it's called tough love
As a parent, how would you deal with a slutty daughter? I'm talking dress, promiscuous behaviour, casual hookups, brings a one night stand home every couple of weeks. There was a guy she liked for a while, but he was using her.
Show her that you care by giving her a good lesson. I'm 17, and I never ever go out and do the usual teenage thing's, like partying, drinking, hooking up or anything like that. My mother is very strict, so I learned the hard way.
You might be going to soft on your daughter, show her you care by laying out rule's on the table. You just gotta be the boss of the house, and ground her from time to time. It may be hard to do, because she's you're daughter, but they gotta learn the hard way.
Ok if she's acting that way, let me tell you something... It's already tooo late. Look, I'd been with a couple of guys by the time I was 15 and mainly it was because I felt like I was ready for it. Turned out all of them were jerks and losers anyway, but it's difficult to see that when you're younger. So your daughter does need some protection from that, but you can't boss her around anymore at that age, because it will work against you and she will want to rebel and be more determined and angry than before.
Really the only way to avoid this would be to make her like a "goody two shoes" from when she was younger, and that way even when she gets curious about getting with guys (which is NORMAL at that age) she will still be a bit reserved about going all the way.
But if she feels like she is mature enough to make those decisions, there ain't much you can do.Just let her be, and hope she learns eventually. But also be there for her when she does come to you!