Should I negotiate my severance? - any advice?

I was offered 7 weeks of severance after 7 years as an HR coordinator, and I have a few days to sign. It has been a long 24 weeks. There is a non-disparagement clause.

Ask for the offer in writing and do not sign on the spot. A day or two to think is normal.

I asked for two more weeks and a neutral reference. They agreed to the reference and added a week.