Maybe you're not cut out to do 4 unit? It seems that 4 unit is the main problem for you, why not talk to your teacher and see what they say about the workload and the quality of your work? Although the HSC is pretty important it's not worth getting really stressed and anxious about especially this early in, you sound like someone the night before their HSC exam who hasn't studied but wants a 99+ ATAR level of stressed so chill! You should try and make yourself study timetable for the week, first draw a table and put in all the things you can't change ie. weekly sport, a job etc. Then each night put in 30mins for dinner and some time to just chill eg. your favourite TV show. Then take stock of how much time you have left for homework and revision. In each section of time put a subject ie. 4 unit maths and also what you want to accomplish in that time frame ie. Finish 10 questions from exercise 3. This saves you all that time sitting at your desk and thinking "Ummmm I should do some homework. What should I do? I forget what I needed to do for maths. I know I'll ring Bob and ask him....." like I did every night this year lolGET ORGANISED! I know it may sound really cliche but I can't stress how much stress it saved me this year (excuse the pun) Get a system happening which organises todays work, todays homework, continuing revision and assessment tasks. These are just some tips to help you make the most of your time, good luck, you've only just started so just chill out! Leave the stressing to trials and HSC!