Questioning and need help (Male 21)

Thank you for taking the time to ready my post. It is lengthy but it was the length I felt needed to relay my story. Please provide feedback and opinions.I am almost certain I am gay. But I am almost certain I am straight. I remember getting my first erection to a friend's mom when I was younger. But I also can't recall ever having a crush on a girl (until my friends started liking girls and I joined the "trend") but remember having a boy I really admired when I was in first grade. He was good at math and basketball, and I wanted to be good at both of these things. It never occurred to me that this actually could have been a crush until recently. I have dreams about having sex with girls (had one last night) but can't get myself to actually liking a girl. I have class with a girl who is beautiful with a very good personality. I like her and the past month or so I have spent trying to get her to like me. Today was the first day I got the impression that she might like me back and I choked and did not talk to her after class. Part of me thinks I am pushing her away because I know deep down that I am gay and could not feel the same emotions she is capable of feeling. I have never really fantasizes about men or been aroused enough to the point of erection. I do find other men attractive, but am very bipolar about having sexual relations (sometimes would sometimes am really turned off). I feel I should mention that I've had sex with around 20 women, and 0 men. I have had troubles performing at times, though, and I continue to question my sexuality. Friends have asked me, "If you have had sex with more women than us why would you question your sexuality? You must be gay." Of the 20 women, I have dated none. I have been in relationships where the girl has liked me but I have not been able to return the favor. I have loved one girl in my life (Jr.High) and I am beginning to question whether or not this was true love or a desperate cry to be straight. I do not understand why I can not fall in love with a woman. Was I born not to love or am I gay?I have at times tried to avoid sex because of not being able to perform. I can never make a second round, I am one and done. I usually do not like having the girl stick around. Am I just a douche or am I gay?P.S. I have nothing against gay people. I have been questioning my sexuality for a long time now and am looking for feedback.