Dt aqa gcse exam hell

Hey!

So I'm currently in Year 11 doing:
-geography
-history
-DT
-maths higher
-eng lit and lang
-science trilogy higher
-RE in Year 10 and got a 9

My teacher left in Year 9, in DT, and we've been through five teachers since then, all of them unqualified and unable to teach anything.

Currently quite behind on the NEA, but I can do this by myself but the theory is quite hard.
They're not teaching us any theory, nor going through the exams.

For the exams, do we revise everything in the CGP revision and the MyRevsionNotes, all materials and categories guide?

It says that we only need to answer the questions in relation to one material category or system for both specialist technical principles and designing and making principles.

Does this mean I skip questions in the exam or do I learn all materials and categories, how do I do sketch questions etc?