Hey! I just want to say it's okay that you're a boy! Because personally I'm bi and I have a girlfriend so I know how you feel. So the girl you're talking about, Ruby. She seems like the kind of girl EVERYONE would have a crush on, which makes it tricky because an extroverted girl such as her may not even be looking for significant other, she might just be flirty on accident.
My advice to you is just, tell her how you feel, even though she might be very extroverted I believe she wouldn't just turn you down, I think even IF she turned you down, she'll do it in an understanding way. Girls like her are a little hard to handle, but when it comes down to it, she'll be totally truthful and tell you whether or not she reciprocates your feelings.
So, gather up your courage, tell her. And if she turns you down, I'm always here if you need therapy.