A really good method of learning from mistakes is physically making a book to keep track of all your mistakes - even screenshotting the question and saving it to a docMake sure you aren’t just doing the past papers, but thoroughly marking them and learning from your mistakes, there’s no point doing a paper if you’re just going to check the answers every 2 seconds. Imo the best way to do past papers is to give them a full go and do as much as you can (in timed conditions ideally), then go through every question you couldn’t do and try to figure it out with the textbook (this forces you to actually learn it instead of just brushing it off and copying the answer) then mark your paper, and write a full line on why you did each one of the mistakes you made in the paper. It’s definitely a bit tedious, but in the grand scheme of things it only increases he time you take by a bit, and is much more efficient.
It’s completely valid to feel a bit demotivated, but it’s not too late to improve (half of your hsc is still yet to be determined!) and you can definitely bounce back
that way after, say, a week - you go back and look through that doc and REDO THE QUESTIONS-- IF YOU STILL CAN'T DO THEM, LEARN WHY YOU KEEP MESSING IT UP
sorry this was a very harsh looking message but it isnt <3