I know how you feel. Stanford, out of all of the places I applied, has the most room to express yourself. Still, I feel like there's so much more that I could have said about my passions, and even about why I chose the courses and activities I do. I wish they could read my extended essay. >.<
Who knows, though? Maybe you expressed yourself better than you thought. And there's always letters of rec.
...Trying to stay positive while expecting a rejection is confusing. xP