Hey
Ok, this year I completed 3/4 Music Performance in which the Performance aspect, counts as 50% of your SS. So theres alot of pressure on you at one instance of time, and its different from the maths and science subjects since, if you slip up- your score does as well. Theres no such thing as consequential marks.
So what I did to overcome the natural stress I felt?
--Practise like a shark is chasing you. Same thing goes for you. If you really want to get there, make it your sole priority in life and do not the whole course, but the unit 3 course, atleast before you start school
--Meditating. Sounds horrible, I know. Boring even. But I tried it and just focused on my breathing. It makes sure your heart beats normally, which obviously makes you calmer
--I realise that because your putting in so much effort, you will be devastated if you make 1 mistake. I get that. But just think. "I am going to freaking rape this exam. I am going to ace this". And you will. Beforee my Music, I cried because of the pressure (especially in my instrument, honestly you should see the skill some people have in Piano), but then I realised, I can only do the best that I can. I was sick of worrying, sick of every emotion I felt to the subject. So I went into the exam, trying to ENJOY my music, and thats what you have to do.
Not sure if you understand my rant. Good luck:)