First, you are not going to be alone for your entire life.
It is messed up that people don't appreciate you. They are probably so busy they haven't been able to see the real you. Many people get so caught up in their own lives and struggles that they don't notice other people. It's a sad tragedy, because they are missing out, and you are missing out. Don't let bad circumstances rob you and them of what might be. There isn't anything wrong with you, it's all about the situation. Sometimes situations are hard to change.
You have to find what you're good at. It's probably something you enjoy. And then you need to make your life's work as much about that thing or things as you possibly can. It's about becoming a fish in the pond you were born for. There's so much pressure for us all to just start swimming, even if we're in the wrong water, or going in the wrong direction.
You are comfortable around your friends, because when you're with them, you can finally be the REAL you. Make friends like that, and keep as many friends like that as you can.
The key to your happiness is to find what you are really good at. Don't focus on trying to make your weaknesses into strenghts. Michael Jordan might have been terrible at Math or History...does that mean he should have focused on trying to become better at that since he was already a pretty good basketball player normally? Allow yourself to have some imperfections because everybody has them. Focus on strenghtening the things you are already strong at. If you are great at the Violin, if you've always just felt at home with that instrument, play it for the rest of your life as often as you can and make it your career. If your gift is in computers...major in computer science. Plan to continue down a path that will lead you closer and closer to the life you want. Once you go far enough, you fill find that you spend time doing something you are gifted at, and that other people finally have an easier time seeing the real you. And you will have an easier time seeing how cool and talented and useful and important you actually are. The world needs you, give the world your best at whatever you're best at. (and be prepared to work very very hard, because that's what it will take)