That's okay! I understand! If you're 17, you're still learning so much about yourself. Plenty of people realize they're queer later in life (and I'm not necessarily saying that's happening here). No one can tell you if you're "bi for sure" except you when you decide you want to identify as bisexual. Plenty of people identify as straight for a long time and then suddenly feel a new attraction to someone in their life and are renavigating their conception of self. This is totally normal, and I wouldn't say that questioning/being curious automatically means that you're bisexual.