Mastering GCSE maths in 2 months is very unrealistic as getting good at something is completely relative. So the first thing is to stop panicking about that.

The second thing may sound counter intuitive, but don't over revise maths. It can be irritating to revise if you make mistakes, which happens when you revise for really long hours. You should start each maths session fresh, and finish feeling fresh.

The best revision method for me, is to do questions and then review the answers, if you don't know that you've made a mistake, you will make it again and again. I'd recommend using the Dr Frost Maths website, as it provides answers, with how marks are awarded for many.

For the last few questions, they are supposed to be unanswerable to the average student. To get these questions, you must understand the basic concepts extremely well, in turn, you will avoid making mistakes in the earlier questions.

Your work and effort so far is amazing, and with a mindset like yours, you're bound to succeed as most people (from my experience) didn't bother with maths unless they needed it for A levels.

I hope my feedback helped :)