hey talia,
it's important to learn the maths content thoroughly and ensure that you really understand what a concept is or how it works. i'm not trying to say that you necessarily did this, but it's common for students to just memorise and rely on the formulas from the textbook and unfortunately this won't help you perform well on the end of year exams because unless you understand the concepts, you won't be able to apply them to these harder VCAA questions. another thing is, how were you using your practice exams? it's not so much how many exams you do, but rather how much you've benefited from each exam. if you don't understand a question or got something wrong, make sure you study the solution carefully to find out why you didn't understand it or why you got it wrong. some people make log books as well to record down every mistake they make in every trial exam they do to help them remember what they've learnt. the more practice you've done, the more confidence you'll have in yourself and that can help to reduce that nervousness you're always going to feel in the real exam. that's just some general advice, i don't know if it helps...
as for whether you should repeat the subjects, that's a tough decision you'll have to make on your own. given that you like maths, at least it wouldn't feel like a burden throughout this year, but as you said it means you would have less time to spend on your other subjects. i can't say whether you should or shouldn't repeat and i think it's best for you to weigh up the pros and cons yourself to try and see what's best for you, sorry about that.
anyway, best of luck with everything
