You could be right, LF. I think it would be difficult to prosecute those charges simply because she moved in with him, which made it consensual. And I seriously doubt that her parents even threatened to file charges. Apparently they didn't care enough to drag her butt out and back home, so they probably thought it was a good thing.
Also, if Misty had filed charges herself, the FIRST thing they would have asked her is, "Do you sleep with him?" In order to claim statutory rape, she would have had to say yes, and the next question would be, "Why are you waiting until now to make this claim if you moved in four months ago?" Bingo... they would have thrown the complaint in the trash can and told her to have a nice day.