Offer arrived, can I still ask for more? - any advice?

I want to negotiate but I am afraid they will withdraw. I have read a lot of threads here and could not find my exact situation. The benefits are decent. Did it backfire?

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

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