Based on this information, I believe that your current performance is consistent with an ATAR between 96.5 and 98.5.
Your position is evidently favourable across your subjects, especially in English Advanced, Mathematics Extension 1 and Engineering Studies, and is highly likely to make a positive contribution to your ATAR. It is therefore important to do your best in your remaining internal tasks so as to maintain your rank in each of these subjects. Not that this is necessary, but any possible improvement to your rank in any of these subjects will also further enhance their contribution to your ATAR, allowing you to maximise your chances of achieving a high ATAR, and possibly one superior to this estimate, because estimates are not decisive.
Your position in English Extension 1, Mathematics Extension 2 and Physics remains favourable, although perhaps not to the extent of your other subjects. This could be an indicator that you should allocate more time and effort to these subjects, which will hopefully allow you to perform at a superior standard, consequently maximising the contribution that these subjects will make to your ATAR and ultimately improving your chances of achieving a higher ATAR.
Of course, your performance in your HSC exams is just as important and must not be overlooked. The fact that they contribute the remaining 50% of your HSC marks gives you a great opportunity to maintain your excellent standard and hopefully achieve your ATAR goal.
I hope this helps!
