I can’t do the HSC

I’m in year 11 (in Australia) and I’m absolutely terrified of the HSC. I’ve never had a good track record with being able to sit through exams due to panic attacks and getting overwhelmed, and I feel like that’s just going to happen with the my HSC exams too. I’m slightly above average in regards to my academics and performance in class but the stress and anxiety of exams drags my performance down. I want to solve this before I sit the exams so I can do the to the best of my ability. Please help me, does anyone have any tips?