This will happen a lot, and you need to pick up the pieces. It's okay, here for you. We've all been through this "friend zone" once in our life. I know I have and it sucks. Huge let down, but it just means she's not the girl for you. We all have one soulmate, so find her. You deserve a great girl.
Dude. A guy can care for a girl without her deserving it. If she is that cruel to you, there is a reason. You're fifteen, dude. Of all the millions of women out there, you will find one that loves you back. DON'T SETTLE. The biggest mistake people make is thinking that they DESERVE a jerk/jerkette. You've got a lot of life to live; don't spend it pining after someone. Quantum physics? Biology? Kid, you're smarter than this. Believe in who you are; you're a smart, independent kid who doesn't need to be begging for the attention of a girl who obviously likes toying with you. My apologies if this is rude, but this is my opinion.
We need to get rid of the term "friend zoned" once and for all...its an obvious clue that you are too immature to be in a relationship to begin with. It doesnt even sound like shes a good "friend" either at this point if she's laughing in your face but by the same token a female is not vending machine that you can put in kindness coins, press a button and get what you want out out of her. If she doesn't like you she doesn't like you. I can tell she is out of your league already and I haven't even met either one of you. Grow up and get over it.
I want you to know that this is going to happen to you a lot in your lifetime. The woman who makes you feel special will be the one to make you feel like crap for the next few days. Let me tell you that they are NOT worth it. They are human, like you and me, as well as any other girl you'll find out there. She is not special, and if she led you on, then she is a whore.
The world is filled with bitches. You will find them everywhere, and very seldom will you find a woman as much worth your time as you are hers. Girls will lead you on, and you need to keep your heart closed sometime until you and her progressed far enough to know she's for real.
Be friends, but don't let yourself fall in love too easily. It's reasonable to let your feelings out so you don't have to keep holding it in, but if she says no, don't cling to hope; the girl changing her mind to fall in love with you only happens in movies. And if she's been playing with your heart, she's not even worth your friendship.
People like who they like. It can't be helped really. You can't help but like her, and she can't help but like someone else, or can't force herself to like you back. Learning to let go, and that things will operate completely different from how you want them, is incredibly important in life.
I will say you have my sympathies OP. You're young, inexperienced, and learning. What you need to do now, is try to move on.
Probably the best thing you can do, and the most mature thing you can do, is learn to look to things and enjoy them without expectations. When you go to do something, DON'T expect anything, and go into it trying to enjoy it. This will be difficult to do at first, but trust me OP, it is an AMAZING, and satisfying way to live, and best of all, you will be free from disappointment and the sadness that goes with it.
For example, you meet a girl. You like her. You be honest. You invite her to do things, to be a friend, or to go on a date. You ask her these things, but you learn to be OK with her saying no to all of them. You leave the ball in her court. You leave her free to act as naturally as she likes, and because you weren't expecting anything, you won't be disappointed. Then, IF she says yes, that's freakin' awesome.
Trust me, it's a much happier and more fulfilling way to live. This way, you'll never be friendzoned, and can honestly enjoy having females as friends. Without all the jealousy, resentment, guilt and regret too.
BAD APPROACH: Be friends second. Feel 'friendzoned', and unable to deal with jealousy, regret, unfilled yearnings. GOOD APPROACH: Be friends first. You can be happy it you stay friends, and be happier if it leads to something more.
sorry if its late, but anyone who likes george carlin, especially at your age, deserves a bit of knowledge.
first, more carlin in your life. read his books. hes funny, yes, but hes also right. and if you havent already, get some bill hicks in your life. he has a book as well. comedy and comedians will drastically help.
second: just because she doesnt see the GOODNESS you do or can do, doesnt make you worthless. if she cant see the awesome things you do, shes not for you. i know how you feel. i truly do, and i beat myself up for it, much like you do. the best thing you can do is succeed and be happy. be the most successful you can be and as happy as you can be. later in life, people will will see this. it will be up to you to decide if you still want these people in your life or to let them watch from a distance.
if youre into quantum physics and biology, KEEP AT IT. when the time is right, you will find a girl that likes you for you.
strive for bettering yourself. the ladies are secondary. dont fall in love until the time is right. and right now, is far from the right time
Keep studying, getting a well paying job will get you ahead in life.
As for the girl. Be honest. Is she thinner than you? Is she more fit than you? Does she look after her appearance and buy better clothes? If so, I'm sure you know some girls that are fatter, dumpier, and don't look after their appearance, who have hearts of gold and personalities fit to outshine anyone's. Why aren't you going after them?
If you want someone thin, fit, and attractive who buys/wears expensive or pretty things, then YOU have to be thin, fit, attractive, and look after your appearance. I'm 140 lbs, 5'5", and I like thin guys. (I ONLY like thin guys.) I know that I have to lose weight. It's just how it works.
I know I'm assuming a lot about this situation, but that's usually how it is. If I'm wrong, sorry. (But if you're thin and fit, you'd have girls falling over you, so...) Working out is not the end of the world, you've just got to do it if that's what you want in a partner. Or, you decide that you *don't* want to work out or lose weight, and you decide at the same moment that you're okay with less fit people too. Those are your two options. Well, a third: keep chasing people that are more fit than you and keep being sad about it.
I also know that's heavy for a 15 year old. You're going to change a lot just as you age, but what I told you is a good piece of advice that you need to keep in mind. Just remember that you have time, and like everyone is say, there will be more girls!! You'll meet new people. This girl doesn't have to be 'the one.' And from the sounds of it, she's not. Do you really want someone who knows you and still wouldn't like you? Noooo. You're worth more than that.
Then she's dumb. You'll find better people. People who don't like you, aren't worth your time. It's your decision whether you want to keep her as a friend or not - if I were you and had feelings for this girl, I'd probably opt to not.