I didn't write notes at all in my HSC. This close to trials you want to hammer out the past papers as much as you can and revise the content on the questions you get wrong.
Between Trials and HSC is where people improve the most so you still have a chance to pull yourself up.
No, find the best possible study method to remember the information from other peoples notes. One problem is that people just keep re-reading their notes which is a passive study method, you actually don't remember much in the exam if your just going to re-read your notes till exams. Search on google for study methods where you can remember information easily and I dont mean memorising. There is a difference between remembering what you understand and remembering just bare words. Along with this attempt practise questions as you get confident with certain concepts.