KW
I used to be the same about meetings!
I hated being shut in and the thought that I couldn't leave without making a scene.
My boss knew about this and used to leave the door open so I could leave if I wanted to and not feel so shut in.
I would take water - a bottle of it, not just a glass and some paper and pen so I could always pretend to be making notes and use it as a distraction.
I am fine in meetings now but I know that they are hard when you feel shut in and panicky and you don't want to make a scene by walking out.
Hope it gets better for you.
Nicola