Hi, so I'm 15. Recently I have been thinking that maybe I am a Bisexual only because recently I had a crush on a girl, when I was younger I used to think what it would be like if I kissed my friends or my heart would race next to some of my girl friends but I always thought that it was nothing and that like everyone else I was straight. But this girl that I had a crush on, I really liked her and wanted to be with her and make her happy, sadly she rejected me for a boy (she's bisexual) and left me confused. I wish to get to know myself better because I always felt this strange attraction to women but I know that I still like man but I don't want to come out as bisexual and be wrong, so I really wish someone could help me.
The person who best understands you is you. Bisexuality isn't 50 percent straight and 50 percent gay, it's any attraction to both genders. Even if you have a little bit attraction toward the same sex, you may be bisexual. Based on what you described, I would say you are bi, however I think you should do some safe experimentation (doesn't always have to be sex, you are 15 after all) and take some time for yourself. It's also important that you don't need to label yourself, however if you think that it will help you define who you are, then definitely go for it. I hope you the best
Pretty clear sign, and I'm sure you thought so too as you were typing it out. Typing it out is a good first step. Writing it here is even better. For the rest, I agree with @GreyCosmo. Too bad about your almost-gf, but it sounds like you understood your own feelings about her.