Haya, you must have overestimated yourself or your writing is bad.
I received a shock in English (79) and realised after reading through this thread that I must have bad writing or overestimated how good my essays were.
I'll be posting something similar in my bingo thread when I have time to get to it, but my raw estimates of 64% in MX2 (88 exam mark), 55/70 in MX1 (91 exam mark) and 80/100 raw in Physics (14/20 mc lol) (92 exam mark) were pretty spot on. Chem, I was off with 80/100, and most likely got a 72/100 (19/20 mc lol) (88 exam mark). My point is that it is easy to overestimate yourself, even when you have done superbly.
Even though 3 of my estimates were correct, and one was slightly off and one was completely off.
And also, I knew my content very thoroughly, but I busted myself with 50 hours a week in past papers in the month lead up to exams.
Did you do every past paper for each subject at least twice? I did that and received more than I needed or wanted.
Did you understand the marking criteria and read over the sample answers?
You may have misunderstood the marking criteria's of the Sciences and possibly even in maths.
The HSC is not just about your information and knowledge, but also the communication of that information to the markers.
I'm sorry, but you have to accept the responsibility and learn from these mistakes. At least you did well enough to get that ATAR, which keeps your options open
EDIT: I had terrible handwriting when writing fast, but that barely affects English, as the marker grasps words here and there.
Luckily, in Maths and the Sciences I would think deeply before putting pen to paper. So in the end I took up all the time of each test to finish (All 3 hours/2 hours of the test). Although I didn't get to check my answers, I did them really good in the first place and had no problem with them, and my writing was super neat and small.