Well, first of all, the golden rule. Don't panic.
Nothing to worry about being a 20 year old virgin. And hey, sexuality is fluid. You don't need a label urgently; you are you, and that's what matters. As for your sexuality, you can be attracted to whoever you like, whether that's men, women, both, or neither, or each in different ways. Give yourself time and you'll come to understand yourself. In the mean time, don't worry about it so much! Do what makes you happy (within the consent and safety of yourself and others, of course).