People can know they're bisexual even if they never had a crush on someone of the same gender. Your sexuality is not about the experience you've had, it's about who you find attractive. If you believe boys and girls are attractive, and you think you could have feelings for both, that is enough for you to call yourself bisexual!
The great thing about being bisexual is that you can experiment. You can also be sexually attracted to a person but not emotionally attracted to them, like you wouldn’t want to date but you wouldn’t mind having sex with them either. Sexuality is something you have to experiment with, in my opinion it’s very complex and you have to find what works for you. Eventually, everyone does, whether at a young age or when they are older! I wouldn’t stress about it.
As a bisexual transmale, I discovered that I was bisexual by dating males when I was female, and then when I transitioned into a male I began dating both females and males when I was more comfortable with the idea of doing so. I’m not as attracted to females as I am males, but it’s different for everyone.
Keep discovering yourself in spontaneous ways!
I think finding out your sexual preference is to figure it with yourself. Do you have feelings for girls? Are you attractted to girls both physically and emotionally?. Also experiencing it might will help it be clearer.
Don't stress about it - the answer will come to you, sooner or later. You don't have to necessarily choose if you're bisexual or not - your life will show you. Just be open to date anyone you like, there's nothing wrong with being unsure.