I know how you feel, I think I wasted too much energy in year 11, I got fucked around big time last year with being sick, having surgery, changing to home schooling, doing accelerated courses through TAFE etc and I had to start and finish year 11 in 1.5months so I think I burnt myself out a bit.
This year I'm just really in the "cant be bothered" mood, I manage to get shit done but It's all half arsed. Now I'm sick again and it's making everything even harder for me to concentrate on.
So yeh, I do understand how your feeling.