I feel the same I often get anxiety at school. This is not a long term help but it helps when in the situation. I like to tap my thumb against each of my other fingers on that hand and count. I also go out of the room and do square breathing and get water. For a long term try to journey when u are having the anxiety like who was there what were the people around u doing. Try to find a pattern and after u find a pattern try to figure out why that particular pattern is making u nervous. Once u get to the route it will be a lot easier to control the attacks. Hope this helps and know school is not everything
Have you been able to analyse what triggers your anxiety at school?