grammar check

Dear all, I (feel sorry/bad) to inform you that today is my last working day in (company name) . I would like to take this opportunity to thank my bosses : xxx and xxx. Thank you for employing me for the past few years. Also, I would like to give special thanks to xxx (supervisor), as she (has given) me a lot of chances, supports and guidance.
Thank you to all of you.

Warm regardsxxx

------------------------------------------- Dear xxx (supervisor) It’s really sad saying goodbye to you. I’m very glad having the chance to work with. You’re both sister and teacher of mine. You always give support and (teach) me how to do and solve problems. I have learnt a lot from you in (company name), however, it’s the time for me to go. Thank you for your everything. I really appreciate your teachings. All the bestxxx
There are some weird and weak sentence, such as "Thank you for employing me for the past few years." People don't give thanks for being hired 就算係多謝都唔係過左幾年之後先多謝..

Dear all I would like to inform you that today is my last working day in (company name). I would like to take this opportunity to thank [] my bosses : xxx and xxx for my employment in the past few years. Also, I would like to give special thanks to xxx (supervisor), who gave me a lot of chances, guidance and support support [].(a lot已在前面集合，三樣都是以名詞寫)
Thank you all and farewell. Warm regards[這句其實可省,因為上句已經是closing greeting]xxx ------------------------------------------- Dear xxx (supervisor) I just want you to know that I’ve been happy working here with you, but I feel little sad in leaving. You’ve been my teacher, sister … and you always give me [] support and tell me how to do things or solve problems. I learnt a lot from you during the past few years [no need to say the company name unless she is not working in the same company]. But it’s the time for me to venture out to try on my own. Thank you for your teaching … I really appreciate your help. Take care and all the best!!! Warm regards[這句其實可省,因為上句已經是closing greeting]xxx