Severance offer, what should I ask for? - what worked for you?

I was offered 9 weeks of severance after 9 years as a marketing coordinator, and I have a few days to sign. There is a non-disparagement clause. Did anyone negotiate and succeed?

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

Keep everything in writing and save the confirmation numbers. It saved me later.