I am in the same boat and I am curious to what others have to say. My daughter cries on a dime. She says she cant control it. This is something that has gone on since she was 12 months.
Let me see - two teachers have suggested your daughter is "mildly" anxious. Hmm..... I think "mildly" might be a bit understated. From what you have written, it appears your daughter suffers from anxiety (this is not anxious). Anxiety is a physcial, mental and emotional issue which causes inability to function in perceived unsafe circumstances (this is what is occurring with the chewing of hair and clothes). If anxiety is the issue, "talking" will not "cure" this (but you have already figured this out). Actually, the opposite works - not talking and patience and understanding and education about the disorder are the things that work. Finally your daughter will need to learn how to "manage" her fears/anxieties in order to cope in her perceived, unsafe world.
If anxiety is the issue, this disorder is one which is usually inherited from genetic components and not one from life experiences. Often those with anxiety have co-morbid conditions as sensory issues and depression. Again, if anxiety is the issue, then your daughter will not outgrow this nor will it go away. But as I said before, she can learn how to "manage" her fears and anxieties and lack of trust in the world.
What to do? Always, the first thing that should be done is to contact your family physician. Therapy is usually not recommended before the child is eight years of age (they just are too young to understand the concepts of CBT - cognitive behavioural therapy). Some doctors will advise play therapy and/or art therapy - and these can help, but they are very limited in their results. If your doctor feels it necessary, he/she might refer you to a medical mental health specialist as a child neurologist or child psychiatrist with experience in anxiety disorders.
There's lots of information on the internet and in bookstores to help you. I might suggest you google phrases as "anxiety disorders in children" or "anxiety and school" or "sensory integration disorder" or similar words to educate yourself on this issue. There are also many books on this topic - a couple -"the highly sensitive child" by Elaine N. Aron is excellent as is "Keys to Raising Your Anxious Child" by Katharina Manassis. But, there are many other excellent ones, as well. Your child's school might even have some books on this topic in their district library (assuming there is one).
The Christmas season is very difficult for our anxiety-prone children - routines change and expectations are heightened and the child's world becomes scary and unfamiliar. It also is difficult for our children to return to school after a prolonged holiday so the next month will not be easy for your daughter. Nonetheless, anxiety is an issue that is very common and highly treatable. Please write if you feel that I might be able to help you in other ways. All the best ...
What do the teachers mean by over sensitivity? is there anything at school happens for them to say this ?