Goodbuy Goodbye to my students

I am a teacher. My pupils are between 11 and 12. It is a very difficult job but also very satisfactory at the same time. You have got We had some bad times but also a lot of good ones .
I have just finished the year This year has just finished and I feel very happy because my pupils have given to me a lot of presents. They cried because they are going to miss to me, then I felt my work is very important. I also cried.

Please. Could someone correct me?

Note:

1. ...then I felt my work is very important. This is not relevant to the previous half of the sentence. i.e. "They are going to miss me" and "my work is very important" are not related. You can say something like "They are gonig to miss me and I them, we shared many good memories together." - this makes both phrases relevant to each other. 

Goodbye to my students

I am a teacher. My pupils are between the ages of* 11 and 12. It is a very difficult job but also very satisfactory. You have You've** got some bad times but a lot of good ones .
I have just finished the year and I feel very happy because my pupils have given to me a lot of presents. They cried because they are going to miss to me.  then When they did, I felt it made me feel like my work is was very important, and I also cried.***

* These words are not necessary, but they sound better.

** Colloquially, speakers of American English are more likely to say "You've got" than "You have got."

**** The changes I made to this sentence were simply for style and clarity.

Goodbye to my students

I am a teacher. My pupils are between 11 and 12 years old. It is a very difficult job but also very satisfactory. You've got some bad times but also a lot of good times.
I have just finished the year, and I feel very happy because my pupils have given to me a lot ofmany presents. They cried because they are going to miss to me. Then I felt my work is very important. I also cried.
Please, could someone correct me?