This is a tough one because I am a teacher and I am a mom of a preschooler. As a parent, I would want to hear it from the teacher what exactly happened. Nothing is worse than hearing your child complain about something and then the teacher blowing it off. Also, how can she get away with not doing any conferences? It is required in our school. Is this a public school in the US?

Anyway, I will be brutally honest. If you complain to the principal, yes, that will make you an annoying parent. Other teachers may react differently to your child (maybe in a more cautious way). This does happen as much as we all like to think that it doesn't. It is almost the end of the school year. If I were you, I would let this one go for now, and hope for a better teacher for next year. It does seem like the first incident when you picked him up could have been a mistake by the office or a miscommunication. The lunchroom thing she cannot comment on because she wasn't there. The cutting hair incident is 100% her fault and she should have called you or sent an email right away.