everyone feels the way you do atm at some point in their life.
i felt like that a while ago, everyone was taken, loving each other, and i still envy how i don't have that someone i can tell everything to, when all fails he'll be there for me.
but to be honest, i dunno - speaking from myself i'm pretty happy at the moment. yeah i'm single, but i'm pretty close with a lot of people, it just depends how you put yourself out there.
i'm even closer with this friend of mine, he means so much to me.. but i suppose it'll take a while for me to know if he feels the same.
as for you being single, just take every day as it comes. theres nothing wrong with it, just try and make friends who are single aswell, that always helps. go out with people who aren't taken, it'll make you feel less like you want someone so bad.
no need to feel miserable, there are over 8 billion people on this earth, less than half of them are happily 'taken' - you have quite an option.
just don't say to yourself you'll never get someone, you're only 17, you have so much more to live for; a job, career, family life etc..
i dunno - just cheer up.