What about mixed people?

I am mixed with white and black. Halle Berry is mixed and so is Barack Obama. Yet all of us are considered black. It is true that are skin is darker, but that's what happens when you mix a light and a dark color together. I've never really stressed to much about the fact that I'm put in the "black" category automatically. But at this rate I think we should have our own category because mixed people (black and white) are everywhere these days! I bring up Halle Berry because back in 2001 she was the first "black woman" to win an Oscar, yet her white mother was sitting right in the audience. Barack Obama is actually mixed two, but of course he's called the first black president. Again, this doesn't bug me, it's just interesting how we label people.
Whenever I have to fill out forms for tests and jobs I never put just one race. I either put "other," or I fill in white and black. Sometimes I know your only suppose to fill out one but I don't consider myself just black. Just recently I had to fill out a scholarship and they said you had to pick out just one race to identify with. This actually made me very upset, because I can't just identify with one race. I was raised by white people and I think that really shows in the way I act. So for this question I thought well I identify more with "Caucasian" then I do "African American." But then the other thing is, if I put white and then they saw me they would probably be confused or ask why I didn't identify myself as black because of my appearance. I don't actually remember anymore which one I identified with, but it was just a bit disappointing, and my parents agreed. Fortunately the world isn't doing that as much anymore. Saying your mixed isn't a surprise, its quite normal. Mixed people of all races seems to be overpopulating the world as we speak. So hopefully some day those mixed options will pop up, so only identifying with one race will be silly.