Should I give up or keep fighting?

I don't know why, when I started reading the different threads and saw how supportive and caring were the people that answer to them, I was overcome by this great urge to cry. Honestly up until today, it never occur to me to search in a forum, and now that I did I am so GRATEFUL!. I read and I see that there are other people that have similar problems to my own, and that makes me feel less lonely. There is nobody I can talk about this kind of problem. So I guess let me tell you a bit about myself:I I'm 17, a junior in high school, never had a proper relationship with a guy, and right now I am questioning my sexuality. I guess if I were to put a label on myself (I'm not a fan of labels, I'm me and that's it) I would say I'm Bi. Why do I think that? Well, as I have mention before, I have not had many relationship ( lets say 1 or two and there were more like good friends than bf) with guys, but I know I am attracted to them... but sometimes I find myself asking if that's true. And then girls! I find myself more comfortable and seeking more of the company of the girls, but that could be because I am a girl. Anyway only a few people know about my feelings and one of them was this cousin of mine ( who is bi) and she was the first one I told face-to-face of my doubts.Then I told her I have a crush with one of my best friends. My friend didn't know anything, and then my cousin came along ( I guess she thought she was doing me a favor and she probably did, because I don't think I would ever had the guts to tell her) and went and told her I was a lesbian, and if that wasn't a shock, she told her I liked her. DOUBLE BOMB! Anyway my friend and I talked and she confessed to me that she was Bi. I was so happy, and I guess I felt a little less lonely. Anyway she then told me that she wasn't interested in seeing anyone at the moment, because she had broken up with this guy that they had known each other for a long time and she loved him still, and they were still talking and didn't know if to come back or not. My heart broke a little at that and I was rejected. Anyway, that was last year, and well since then I don't really know what happen there, and I am afraid to ask, she looks so happy, I don't want her to remember him. I'm still not over here and I was thinking that maybe, I could confess to her again, since Valentine's is around the corner. This time I want to do it properly. I don't know she rejected me once, maybe I shouldn't do it. I know that there is a big possibility of her saying no again, and just thinking about it makes my chest hurt. What do you think I should do? Thank you for taking your time reading