How much room is there after an offer? after 4 years as a customer-service rep

It is the first offer in 4 months and I do not want to mess it up. There are 4 people counting on me, so I am trying to be careful. The benefits are decent. What wording worked?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.