half of my teenage life I have only liked girls but now I have very little attraction for guys. I don't know what to do.
Sounds like me right now. I never really questioned things until now when I realized that I started being attracted to guys as well. I would classify that as bisexual, but only time will tell what it turns into. For me, it started out with me only liking girls. Then recently I started liking guys just a little, then more, and then more. Eventually it came to basically evenly liking guys and girls, and then now I feel like I like guys more. In time, things keep changing, and I think it won't hurt to identify as bisexual until you're fully sure, because, if at that moment you feel attracted to both guys and girls, regardless of it it's only a little bit of attraction, that would be bisexual.