How much room is there after an offer? (Detroit)

I received an offer as an accounts payable clerk and I think the pay is a little low. It has been weighing on me all week. The hiring manager was friendly and open. Did it backfire?

If they say no, consider asking for something else, such as a review in six months.

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