Gay Thought ??? lol?

Lately this week ive been thinking what if im gay ??? (i know im not because im never attracted to same and no girl stuff lol) But im just curious...how will u know if ur gay...could it be just a phase im going to ?? im turning 18 on octover fyi.. just to let u guys know if i think something my mind stays focus on it until solved =/ ... i never had a girlfriend nor kissed a girl other than mom or sister lol ... BUT i cant wait until i find that girl...(not to be rude...if i do look at explicit content its always on girls...and if i see gay im like ewww lol....n i would fantasize on girls from time to time lol...any commentt????