I've explained EAS in this thread :
http://www.boredofstudies.org/community/showthread.php?s=&threadid=24845
What you need to do is, prove that these two years, yr 11 and 12 has been greatly impacted by Your cause in what way, how bad was it, was it a cause that could not be prevented? What documents do you have to prove for it, etc.. I trust that you're applying for the EAS truthfully as opposed to alot of people i knew who liked the idea of "hey bonus hsc marks, lets get it" it's stupid, i mean for the people who have death occurances in their family, they might miss out on getting the EAS because of other stupid people claiming it, for the sake of it. It's just unfair, talk to your co-ordinators about it, you can get a form off your careers advisor, i urge you to read through the thread above i have given the link for, ive explained all that u need to know as well as providing a link to e-booklet of the eas from the UAC site.