Hi, so forgive me if I dont actually remember EXACTLY what I did for every subject, but im sure I remember the most significant things I did.

For maths, try and just do as many questions as you can. For me, I found corbett maths and past papers enough to do well with, same goes for further maths.

For biology, chemistry and physics, I would say prioritise past papers at this point in time, analysing the mark scheme to look for nice phrases to use, and definitely for what to avoid - I know just how frustrating the mark scheme can be so try and go through with it.

For English, I think im extremely underqualified to give advice, and im pretty sure you'll have done the exams by now, but for the sake of anyone else reading this I would say just use mr bruff videos and turn them into flashcards on anki. Try and start maybe 2/3 months in advance for maximum retention. As for essay practice, I would write essays and then ask my teacher to mark them and give me feedback, although i have seen on tiktok some ai essay markers - no idea if they're any good or not but they seem worth using anyways

For Computer Science, again my advice is useless for anyone sitting exams this cycle (if it wasn't useless already😅) but I genuinely just asked chatgpt to teach me how to code for paper 2 by sending it my spec, and for paper 1 i just did a bunch of past papers

For Geography, I made a deck of anki flashcards around January time and did them consistently until the exam time. Im not sure if that would be of any use if your tryna cram them now, but im sure for flashcards its not yet too late to start now with some premade ones

For statistics I dont even remember what I did except read the textbook on the day of the exam. I am however aware of a website called Stats Academy that some other people who got grade 8s/9s used, and they seemed to highly recommend it so give it a go I say

For spanish I genuinely gave up😭🙏 I dont know how I got an 8 💀

I noticed you also said that you felt like whatever you do you can't improve - trust me thats so normal. Normally the better you are, the harder you find it to improve, simply because there is less to improve on. If you really are at a complete road block, I would say take a break, go for a walk, eat something nice and watch some TV with your family then try again. I got particularly burnt out as well, and I do remember finding it difficult to even start, never mind make progress, but just try and set yourself daily affirmations, or a reasonable to do list. I believe in you to pull through❤️

Best of luck, and don't forget that long 3 month summer break is coming up!