What is happiness? Who am I?

What is happiness? As I get older I realize more and more I don't know what true long lasting happiness is. I get a taste of it every so often, but it is quickly taken away. It getting to the point where I'm starting to believe it is something I don't deserve. The bad thing is that to most of the people in my life, I am one of the happiest people you would ever know. I hate that I pretty much hate myself, it hurts but I can’t help it. I just see so many flaws in myself, and I can’t help but feel like a huge mess. The worst part is that everyone I know thinks I self-confident, cool, and just know what I want, but in reality I’m none of those things. I’m just an awkward, unhappy and lost person who sleeps all day because then I can be stuck in a dream world, I don’t want to live that way forever. It's hard when people see you one way when you are the complete opposite in .. Its like I'm two different people, everyone sees the one that is just happy-go-luck and always in charge, and I see the one that is lost and just searching for some hope.. I can pretend to be happy because it’s easy, no one wants to be around a depressed, overly paranoid girl… so I smile and talk a lot to get by. I have no one to talk to about the way I am. At this point I'm only happy when I'm listening to music alone or sleeping which is a bit sad. I don't understand myself. Who am I?