You are lucky to discover the poly- option at a young age! Remember, polyamory is about LOVE, and don't let anyone tell you otherwise. Conventional, mainstream Americans will try to convince you that the only genuine "romantic" form of love is monogamous. Well, that's nonsense. It's just like folks insisting that gay/queer folks don't really love one another--that it's just about sex, and "immoral". Nonsense!
Good for you for choosing to think these issues through for yourself!