I am so sorry for your loss. I can empathize. I have always had a pet. DH and I are so "pet-whipped". They are family. I know it will be a rough one when the time comes for one of our guys.
It sounds like you and your dog had quite a bond. That is such a reflection on the way you cared for her. Sounds like you guys were lucky to have each other.
Don't feel bad about thinking about another dog. That doesn't diminish or lessen your love for your dog that just passed. In fact, I can't think of a better way to honour your dogs memory, than by saving another lucky dog.
When the right time and the right dog comes along, you will know that you are ready.
I wish you as much peace as possible through this tough time. I'm sending some hugs your way. Take care, hon.