i wouldn't worry too much, a lot if not everyone else feels like this even if they don't say it. The best thing to do is find some coping mechanisms like breathing exercises or counting certain number patterns on each of your fiver fingers. Also i would recommend sitting past papers at home in the time given in a real exam, this helps prepare you to finish the paper in the time given and it can help you practise your coping skills. You can do this!<3