I too was the quiet, sensitive child, and am still a pretty quiet adult, despite being a trained teacher and having had lots of customer facing roles.
It didn't stop me living overseas or having a good career for many years or from making lots of good friends once I was in an environment that suited me where I felt safe and comfortable and that I wouldn't be laughed at or criticised or belittled for just being me. And over the years I've learned to pretend I'm confident in certain situations, though it exhausts me and most of the time I'd rather be at home with the cats and a cup of tea.
Overblown extroverts who love the sound of their own and other people's endlessly yattering yakkiness really exasperate me. I've met a lot of them in my life in the form of jolly hockey sticks PE teachers and managers, class and office clowns, nightclub-loving-gals-and-guys, over-the-top soldiers, and the like.
I'm one of those people who works better in one-to-one relationships, because then it is harder for people to hide who they truly are.
Many, many writers and artists, for instance, are very quiet, and actually a surprising number of actors are very shy off stage or screen. Besides, if everybody was an extrovert, who would listen to them drone on and worship at their feet? What's that saying about empty vessels making the most noise again??
I think the book someone refers to up-thread might be "Quiet Power: The Secret Strengths of Introverted Kids" by Susan Cain. She also wrote "Quiet: The Power of Introverts in a World That Can't Stop Talking".
www.learning-mind.com/the-quiet-one/ might also be a useful website for you.
We live in a culture where being over the top and noisy is, unfortunately, valued over being quiet, observant and contemplative, but there are plenty of other cultures where the reverse is true.
(And you know, the teacher might want to have a serious think about a) her classroom management style and b) the fact that if, as she claims, your daughter just wants to curl up into a porcupine-like ball whenever she comes near her, why is that, exactly?!)
It also sounds as if the teacher might benefit from brushing up on her Myers-Briggs, Enneagram, Belbin Team Roles, and some of the more recent stuff like Insights, www.insights.com/products/insights-discovery/
We did the last one in one of my workplaces and we all got so much out of it we were talking about it for weeks afterwards. It made me and my then deputy really understand why, although we liked one another and respected one another, there were times when we drove one another up the wall. The full insights thing has a cost, but they do have a fun free quiz on the site.
All the best to you and your daughter.