As a naturally quiet person myself, I sympathise. I've spent my life having it minted out to me that I'm quiet, as though it's something I having noticed, should be worried about and should take steps to change.
Constantly being criticised for my quietness was the catalyst for my self esteem and confidence taking a huge nose dive by secondary school, as I thought there was something wrong with me.
The criticisms followed me into my adulthood relationships and career. I turned to drugs and drink to make me more like others... louder, more outgoing, less inhibited. But I loathed myself for it.
It took me to meet my now-DH to finally realise being just 'me' was ok. Being a quiet introvert isn't some kind of bad health condition that needs to be cured!
DHs DM still doesn't 'get' it and over the years has pushed and pushed for me to be more "sociable" than I'm comfortable with, as she thinks my personality "isn't normal" and "not good for her GC" (My DS).
But I no longer let anyone make me feel like shit for who I am. I'm not loud, I'm not comfortable being centre of attention, I don't like crowds, mixing with lots of people and loud noises. I like quiet, I like alone time, I like walking, being amongst nature, reading, arts and crafts, gardening etc. And that's ok. I don't need counselling, any more friends or to get out more!
Tell your DDs teacher your DD is perfectly fine as she is.