As it works here, school finishes at the end of the year, not midway through it (due to the seasons being flipped). But, I am finished this term. I'm not really considered a nerd at my school, either. Probably because I'm sociable. XD;
Technically, I should be a year below what I am, but I was let into my first year of school before I should have been. But the work is still ridiculously easy. :\
Interestingly enough, when I reach your age, I'll be doing IGCSEs (International GCSEs) myself. I'm a bit like you - my classes are ridiculously easy. :/ I'm top of my year with little effort at all, but for some reason (in my country at least) putting you up into a higher year is just something that I've never seen done.
That sucks. I've never been ill for an extended period of time, the most being about three days, so I've never had that experience. But some of my friends have, and I know they had to work really hard.