Omg i'm so sorry, this is my first time posting and i just realised how bad i formatted my text. Im so sorry.
No problem at all, milo! Welcome to the forums!
With the scores you have, achieving an ATAR in that range is definitely not impossible. To improve, think about what it was that impacted your marks. If your study and revision habits weren't that effective, try and revise regularly and see what study methods work for you. Past papers (especially when mirroring real exam conditions) and practice questions (and hopefully help from your teacher too) are invaluable.
This article with study methods is a good place to start. It might be your exam technique (like you may have spent too long on a question that you didn't get) or your understanding of certain topics that could have impacted your grades. There are also many subject specific and other general tips and tricks for the HSC so have a look around!
Remember if you don't achieve your desired ATAR, there is always another way to get to where you want to be. Just try your best so that you can look back and be proud!
In short, you can still achieve your goals, even if you aren't where you wanted to be now.
Good luck