So, it's not exactly a crush. But I am attracted to my best friend quite sometimes. And I don't think about him all the time...just when we're having fun or something. I know I'm not gay because I've been and still am attracted to girls, but this feeling is just weird..I don't know.

That is... if you want to make a move. If not, it might just be a phase. Maybe this is a person with whom you feel really comfortable with and so you feel like you love them? I don't know. For now, don't think about it too much and just chill out. :)
You wrote, "I'm attracted to my best friend quite sometimes... I don't think about him all the time."
I read it as, "I'm sexually attracted to my best friend."
I think that's so cool. No matter what anyone tells you, they have felt the same way. Now, one of two things will usually happen. Either, you'll both be naked in bed and making an incredible life-long memory, or you will stay silent and think about him whenever you masterbate.
I have been in this situation. We ended up in bed. The bad part about it was that afterwards, our friendship deteriorated. We allowed 'confusion' to take over and we pretended it didn't happen. That is a friendship killer.
If it doesn't happen with him, I guarantee you that your attraction to him will be transferred to another guy.
Just be careful, please. Is a long time friendship with him really worth a few hours in bed with him? I know you stated that girls are still attractive. I love them, too.
You might be one of those strong people who can admit the truth and trust yourself. My guess is regardless of what may or may not happen with your best friend, will happen with another guy in the future. It's natural and normal. Be happy you have the guts and the brains to see it already.
TWO RULES OF LIFE:
1) Don't sweat the small stuff.
2) It's ALL small stuff.
"Good Luck To You." You sound very intelligent. I'd like to know how you're doing in a month.