Given this information, I believe that your current performance is consistent with an ATAR in the low to mid 80's range.
Your performance is essentially of a similar standard across your subjects which, should your ATAR goal be higher than this estimate, would imply the need to focus on improving your ranks across your subjects. Whether this is possible depends on whether you completed your trial exams. If you have, hopefully you will have performed at a standard that would contribute to rank improvements in each of your subjects (therefore placing you in a better position as you approach your HSC exams). If you have not yet sat your trial exams, you have a good opportunity to prepare to the best of your ability, and hopefully perform at your desired standard.
Beyond this point, only your HSC exams remain. Given the fact that they contribute the remaining 50% of your overall HSC mark in each of your subjects, they constitute a great opportunity for you to either solidify or enhance your performance (depending on your own goals). If your ATAR goal is higher than this estimate, this means that you will have a great opportunity to make a comeback and reach your desired ATAR, provided you prepare for your HSC exams to the best of your ability.
I hope this helps!