what if, and other whiny thoughts

I feel like "the rest of my life" is rushing at me, and I couldn't stop it if I tried. But I can't get any kind of picture of what that will actually look like. I know its not exactly original for a teenager to have a "who am I" moment, but seriously, who the fuck am I? I only know high school me, (and I don't always get her that well.) For the longest time I've been defined by where I go to school, who I sit with at lunch, what activities I do, what classes I like, what grades I make, etc. I know those things aren't all there is to a person, and its the fundamentals that scare me. In a year's time I'll be starting over, no longer surrounded by the expectations of people who know me, expectations I've always been too happy to meet. What if I don't like what's left at the bottom of me that I have to build back up on for new relationships, new attempts to squeeze myself into the social norm without actually changing who I am. I've caught fleeting glimpses of the underbelly of my soul,  and they aren't always pleasant or encouraging. Don't get me wrong, there are plenty of moments of clarity that I'm pretty content with, introspective epiphanies that inspire some confidence and pride, but what if those aren't enough? What if I'm simply too weak for the "real world?" Everyone around me is so certain that I'm going to be more than ok. I've got the grades and test scores to get into a good school, enough money in the family to get by, enough love and support from my parents to cover the inevitable blunders. But what if me as a person doesn't measure up? What if I stumble out of college without a clue what I want or how to get it? Where's the little box on the common app for whether or not you will be able to function as an adult human being?