From this information, you seem on track with an ATAR in the high 60s range. Your performance across your subjects can be classified as moderate to low, with some subjects being different than others.
Mathematics Advanced is your best-performing subject and is likely to make the most significant contribution out of your subjects. You can improve your overall performance in this subject by doing well in your HSC exam, for which you would need to prepare thoroughly.
Your performance in Ancient History and Legal Studies is slightly less favourable compared to your position in Mathematics Advanced. This means that there is a larger room for improvement in both of these subjects when compared to Mathematics Advanced. To enhance the contribution to your ATAR from these two subjects, it would be good to allocate additional study time towards them as you prepare for their HSC exam.
Lastly, Biology and English Standard are your lowest-performing subjects. This means that these subjects are likely reducing your ability to reach a higher ATAR at this stage. Additionally, these are the two subjects where there is the largest room for improvement. As such, you may wish to consider placing additional emphasis on your preparations for their HSC exam, allowing you to improve your overall performance in both, resulting in a better contribution to your ATAR and ultimately a higher ATAR.
I hope this helps!