Does it matter? The reason people ask this is because they think they have some sort of duty to protect you from the scary thing that is being not-straight. If right now being non-straight seemed right and you found someone you wanted to be with, what is the point of saying "Well I'd better not go for it, I might be straight!" What are you going to do, wait your whole life hoping the phase ends?
You don't. You enjoy it while you it's there. I've been out for nearly a year now, and I still question whether it is a phase or not, but at least I know that if it is and I end up straight (hopefully not) that I won't have let it control my life. Embrace what you're feeling and love it.
I dont think anyone will actually really figure out this question even for those who claim to be straight. You love who you want to love and be okay with it.
