try to just get on with your work and not think about the overwhelming feelings of exams and no time etc. fact is, sure we don't have much time but if the previous year students were able to do it, then it should not be any different for us. Not like they had more time than us, and term three is known for being the sac overload term. so just get on with your work and you will be fine.
p.s i used to think the same for many weeks that i would be completely crammed with sacs, and always thought how on earth am i really gonna do this all, yet the week would pass and i would have completed everything required.
one thing that yr 12 has taught me was that we all have more will power in ourselves than ever thought. i have done much that i believed exceeded my ability. each time i proved myself wrong.
good luck!