A letter to my English teacher
Dear Miss Cheung,
I am very lucky to have that we have met you during my at the last year of secondary school. It is has been wonderful our pleasure to have a such kindful and thoughtful heartful English teacher. Though honestly I feel a bit sad that you only taught just teached us for a few months, but we still learnt a lot from you. Thank you for being our English teacher this year! It was really helpful.
Yours truly,
Wendy
A letter to my English teacher
Dear Miss Cheung,
I am very lucky that we have met you at (during) the last year of secondary school. It is our pleasure to have a such (such a) kindful (kind) and heartful (I don't understand this?) English teacher. Though honestly I (I honestly) feel a bit sad that you just teached (taught) us (for only) a few months. (Nonetheless), we still learn (learnt) a lot from you. Thank you for being our English teacher this year! It is (You have been) really helpful.
Yours truly,
Wendy
I would personally write it like this. :)