am i bisexual?

I'm 18yo btw and... I have been confused abt my sexuality for past few months. I'm pretty sure I'm straight. I mean i have always liked boys till now but not to the point of dating them.
Umm... is it normal if u think ur friend is actually like hot and u wouldnt mind kissing her or anything and like its like u can be fine havng sex with her?
Also, I've realized when i was in all girls middle school i was kinda curious abt this girl cus she looked a little boyish. 1 of my frnd caught me staring at her and teased me abt liking her, it scared so much that I just started repeating- she's a girl... she's a girl in my head lol.( I didnt know abt gay/lesbians).
But now i have realized that i wouldnt mind dating them?

but like in the past i was crushing really hard on this guy almost like for 2 yrs (didn't feel like that towards a girl)

Is it cus i've read too many yaoi/yuri? (which i just started reading for the past 9-10 months) idk
I am also not grossed out by lesbian porn or anthing but not sexually aroused either same w/ str8 porn.
Is this bcus of my hatred towards men? (idk if its make sense but yeah).
But like.. I have fantasized about having sex with both genders.  
I also took up a quiz it said I am fluid hetero?
So am I like st8 but can also like girls now?