Another thing no one has mentioned yet is your revision techniques. It’s no use just like re-writing notes and hoping it somehow stays in your brain. Implement active revision such as flashcards, active recall (try re writing your notes from memory), etc etc.
the harder it is, the more you learn and build neurological pathways in your memory.
I’ve spoken to so many people who revised hard for GCSE’s, spending hours on end revising by rewriting notes, and disappointed with their results at the end.