I'm straight, 100%. I know because I've been very close to trying, and figured out I was too straight to go through with it. If you had asked me when I was 18-24, I would probably not be so sure. Being "bicurious" around that age seems to be quite common, but is probably (my speculation) not closely linked to the proportion of people who are actually not straight.
I had something similar and was mildly crestfallen when it turned out that dating a dude feels extremely similar to dating women. I thought it would be like... orange-flavored? Or at least spicier? Religions hyped it up for so long, I thought there'd be some sort of difference. Kinda just feels like dating a best friend, regardless of gender. :)
I still find women attractive, but I'll be damned if this relationship with my bf isn't the best one I've ever had.