Oh big to you. They know just how to push our buttons and really wear us down to the point of not recognising ourselves sometimes. You are not the first and won't be the last to lose it with your child.

I have no real suggestions as it sounds like you have tried so many things, and my kids are not yet at that age, but are there some resources at the school that may be able to help to give you some strategies? It doesn't sound like she is undisciplined, moreso just unable to deal with emotions and self soothe. A psychologist or someone may be able to work one on one with her to help her calm herself, and also give you some ideas of how to diffuse the situation.