Given this information, your current performance seems consistent with an ATAR in the high 70s to low 80s range. More specifically, that would be an ATAR between 79 and 81. However, improvement to your overall performance through favourable HSC exam performance can help you reach an ATAR that exceeds this estimate.
Modern History appears to be your best-performing subject, especially given the fact that you are ranked first, giving you a significant opportunity to maximise your overall result in this subject if you achieve the highest HSC exam mark within your cohort. In such a case, the moderation process would work in your favour, meaning that your overall HSC mark would be made equal to your own HSC exam mark. If all goes well, this subject can make a very positive contribution to your ATAR.
Mathematics Advanced and Design and Technology are some of your better-performing subjects, and can as such make positive contributions to your ATAR. You should therefore ensure that you thoroughly prepare for their HSC exam to ensure the best possible overall result in each. The same can be suggested regarding your performance in Studies or Religion I, although to a slightly lower extent.
On the other hand, English Advanced and Ancient History are your lowest-performing subjects. English Advanced is more concerning than Ancient History because it must count as two units towards your ATAR, whereas Ancient History can potentially count as one unit, the other unit being SOR I. At the same time, this indicates that this is where there is the largest room for improvement. Hopefully you did well in your English Advanced HSC exam. You may wish to consider placing greater emphasis on your preparations as you near your Ancient History HSC exam.
I hope this helps!
op's marks are at least an 80+