It's great that you have managed to learn things from JAC because their teaching pace is pretty fast! I remembered that I can't even learn anything last year when I went because it is really fast for me! This proves that you have the ability
I don't think it is necessary to know trigonometry but since you know some that's great!
It's normal to feel dumb as it is coming closer but DO NOT GIVE UP! Since you've prepared, you're halfway there! It is okay to feel nervous but DON'T let it affect your exam performance! I know many people who are smart who should be able to get in but because they get too nervous and didn't perform their best
If your teacher is willing to help you at school, GREAT! (my teacher wouldn't because she describe it as 'a plan to get out of school') Ask the teachers and watch youtube videos together! It will help you lots!