Should I negotiate my severance? (Fresno)

I was offered 3 weeks of severance after 3 years as a bookkeeper, and I have a few days to sign. It has been weighing on me all week. I do not want to leave money on the table.

An hour with an employment lawyer cost me a small fee and made me feel much safer about signing.

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