Should I negotiate my severance? - any advice?

I was offered 11 weeks of severance after 11 years as a mechanic, and I have a few days to sign. It has been a long 10 weeks. There is a non-disparagement clause. Should I see a lawyer?

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

Read the release carefully. Mine included things I did not expect, like a non-compete.