Meh you never know.
I was estimating something low 80's at start, but near the end I thought I could do well enough to get a high 80's ATAR. I ended up with 96+ lol and did not expect it at all.
Its not like your subjects are going to scale you down lol. You could get 99.95 with those subjects actually theoretically.
For a 91, you could get it with 85+ in everything.
97, maybe a 90+ in everything could suffice. It will be achievable for you. Just depends how much you want it. My advice is to just give it your all and in the end you will be pleased with your results
Also, you are still in year 11. There's still quite a bit of time to pick up your game.