It's tough to help you out, I can't say what you're feeling or why, but maybe I can speculate. Maybe your friends aren't a good match for you? I have a couple groups of friends and I know that I get very fed up with one of them. They just make fun of one another, mainly me haha, and seem to have no deeper thoughts or concerns than food, clothes, farting, screwing around, and trying to fit into being as cool as they can. I can't relate at all, and most of the time I end up staring up at the clouds or sky wishing I wasn't there, or trying to make them see things in a different light. They are very narrow minded and can never think of anything to do. Always 'bored.'
Maybe you are similar? Can you really express yourself and open up? Can you joke around? See my sense of humor is completely different from my friends. I am more of a harmless jokester. These guys are hurtful. Gets quite annoying. Don't know why I even bother with them. I don't think I will much more.
If you are happy with your friends, and are fairly tight with them, but just finding yourself discontent, you can try to practice mindfulness. You seem to constantly wanting to be somewhere else, but the secret to almost everything in life is being happy where ever you are at that moment. Take some deep breaths and realize where you are, and that there is no where else that is really better than where you are at this moment, and be fully aware of what you are doing. Try to think of it as there is nothing more sacred, more important than what you do in this very second. It's the only moment you can affect. You do no good wishing you were somewhere else, or in the past or future. Anyways that's my shpeel. Good luck.