Don't sweat the HSC - It's a wank and not much more. It's geared at getting you into Uni, when you get to Uni the HSC means jack shit.
I push my students hard to get results, but I also make sure they relax and enjoy themselves. It's called balance. If your folks are pressuring you then take them aside and talk to them about it. There's enough pressure without it coming from home. 10:1 that your folks don't even realise how it comes across to you.
If it's too much pressure (kids today... when I was a kid...
) then think about pathways doing the HSC over 2 years. Some of my top students have done that and walked away with 99 UAIs.