So sorry about your buddy. I know my 14+ year old chocolate lab is getting up there and it is going to be a tough one. Like yours she has been a great friend. Her hips are getting weak and she is slowing down.
Can't give you any advice on when you will be ready to get a new family friend, it is a personal thing that your family can only dicide when you are ready. Just keep in mind it is much easier to house train'em in the warmer months then winter, if that helps. I usually plan spring just for that reason.
Here's to her and God bless
On Charlie's note, I use to have a bumper sticker on my truck that read, "the more people I meet, the more I like my dog."