How to write a thank you letter

I am a non-native English speaker. I would like to write a thank you letter for my daughter's English teacher.
Can you all please teach me if it is correct and it does't sound tedious?

Thank you very much for being such a fantastic teacher for .... .
A year ago, before ...... started to take your lessons, she was just like a baby.
As soon as she started to take your lessons, I was surprised to see her big change. I have been seeing so much improvement on her English since you became her teacher.

..... is so lucky to have a teacher like you.
You always care for her and you are always very dedicated, creative, positive, and energetic.
Also thank you for being patient even when she is naughty.

I am grateful and happy to see her progress and looking forward to seeing further more from now on.