There are lots of slightly different ways to say this. Here is my suggestion:
"I work for three weeks every month, five days a week, from 7am to 5pm."
"Every month I work for three weeks, five days a week, from 7am to 5pm."
I wouldn't mention the year, it isn't necessary.
Also, numbers 4 and 5 say that you work *every* week, but numbers 1-3 say that you only work 3 weeks every month. Which do you want to say?