I will obviously keep trying, but I don't even know where I'm going wrong......
This is your first problem. Imagine if a race car was moving really slowly, no matter what the driver did, what do you think would happen? They'd get the car looked at to see what's wrong.
Simply sitting down and smashing through questions to see if you can answer them is not an effective method in your case. You need to sit down with the questions you've already gotten wrong, and figure out *why* you got them wrong. Once you've done that, then you can think about re-learning the theory that you're struggling with. After that, THEN you can think about smashing through questions again (until you get one wrong, and the process continues).
The easiest way to get to a 99.95 ATAR is to make no mistakes - however, in order to make no mistakes in the exam, you need to make them before the exam first. It's only after you've made them that you can work on never making them again.