How much room is there after an offer? - 2 months and counting

I received an offer as a school bus driver and I think the pay is a little low. There are 8 people counting on me, so I am trying to be careful. I have a competing interview next week. Did it backfire?

I thanked them and said I was excited but hoped we could talk about the pay. They came back with a bit more.

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