Negotiating an offer, is it too late? - 5 weeks in

I want to negotiate but I am afraid they will withdraw. I have been trying to stay organised about it. The benefits are decent. What wording worked?

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 12 months ago, and it settled down once I kept a simple log of every call and form.