I know some people will just sag it's puppy love or how can you love at the age of 12 or whatever. But with me is different, I'm much more mature and I believe in love WAY more than any other 15 year old.

You probably aren't going to like my answer but what you just said is what pretty much every teen your age is thinking/saying. I am not going to tell you that you don't love her, I would have no way to know this and I do believe love is possible at a young age. What makes young love/puppy love so iffy is how teens tend to behave and react to it. For example, you are considering suicide at age 15 because you like a girl you haven't actually been rejected by. Your life hasn't even started and you want to end it. That's not a stable reaction and I would say the high intensity of your feelings is due at least in part, if not entirely, to your age. Your hormones are off the charts which isn't entirely abnormal; what is worrying are the thoughts of suicide and depression. For those, you need help.

I know you are probably shaking your head at this but when I was your age, I wasn't what I would now call a great decision maker. I was better than some of my peers but I still screwed up a lot. Screwing up will happen all throughout your life but as you get older, if you allow yourself to grow and learn, these screw ups won't be quite so awful (hopefully). Relationships even out. For example, my first relationship was from 19-23. It was awful. While I had the ability to love and commit, he was awful and my reactions to him were awful. A more experienced adult would have bailed by age 20. I stayed much too long. But now, at 27, I am married and we are so much more stable. We have our squabbles but we handle them much better. It's our age and experience that makes the difference.

This is getting pretty long, and for that I apologize. But I will leave you with my similar experience - I met a boy when I was 9 and he was 10. He (and 4 others, surprisingly) had just flunked 4th grade (in a very small school, I don't know wtf happened) so we went through the rest of our studies in the same classrooms. I liked him all the way to 10th grade. Never said a peep. Today, now that I'm 27 and he's 28, we are vastly different people. Not at all compatible. Life happens, people grow. Try not to hang your entire future on this and talk to your school counselor.