Offer arrived, can I still ask for more? - 9 months and counting

It is the first offer in 9 months and I do not want to mess it up. I do not usually post, so bear with me. The hiring manager was friendly and open. Did it backfire?

Thanks for writing this out. I went through something close to it 9 months ago, and it got easier once I kept a simple log of every call and form.