The Dreaded Future

As a teenager who is still in school, the future can look quite scary. I guess it is for anyone really - apart from children, to whom the future is a place filled with flying cars and teleportation. But I mean, everyone at my age has a rough idea of what they want to aim for already, what they want to achieve throughout the end of school.
I don't. I feel as if i should know now. My GCSE options have been chosen, and I am working towards them now. But I mean, what if what I am interested in now, will mean nothing to me in 5 years when I am heading off to University. This scares me. Should I know what I want to be yet?
Everybody has their dream job, like it would be amazing to become some sort of model or professional dancer. But those dreams are crushed by secondary school. They bring you back to reality, and it's not the nicest of places. Options are limited, so there's not going to be something out there for everyone, I know. But doing something I love, and earning a living is my aspiration. That's MY goal. But that's all I can say about it. Who's to say I might be working in a hospital in 10 years time, a path I never would have even considered at school. I wont know until I'm older, but is that too late?
Anyway, sorry for boring you with my own problems,
Smile,
Lizzie x