Is it normal that i don't know what my sexual orientation is?

I am 19 and I have never once had a crush on or been in love with anyone. I wasn't into guys or anything throughout middle school, I don't even know if I truly had any attraction to anyone ever other that thinking someone was good looking. I have never once had a crush on or was into anyone. I have been single all 19 years I have been alive. I have been asked out, a number of times, but I turned every one of those guys that asked me out down. One of them being my best friend through all of high school, he has made it quite clear that he really likes or i should say is in love with me and that he couldn't see himself with anyone other than me, though I could never see that happening I have absolutely no attraction to him romantically and could never see us being anything more than friends. There is also another guy who everyone keeps saying I should go out with and he has also made it clear that he likes me. Thing is I don't know if I like him like that, I don't even know what my sexual orientation is. I have been questioning it for a few years now. I don't really know how I would figure it out either. Though I can see myself having sex with another woman sooner than i would a man...I kind of just think that when I fall in love it wont matter what their gender is I'll love them for who they are not what they are. I am clueless as to anything regarding dating, relationships or anything along those lines despite being a lover of love, and watching/reading romance after romance... I really don't know what I should do or where to go from here...