My kindest thoughts and wishes to you. It is heartbreaking to lose a beloved dog, I do know.
One thing she did know, was that you love her. They always know. Yes, they miss us when we are gone for a while, but I am sure she was cared for in your absence.
I have noticed that dogs can and do adapt to the absence of a loved one. They feel it, but calm down a lot in a couple of days and their normal survival mechanism overrides missing us to a great extent (although they certainly will remember us, maybe in their dreams, and definitely when they see us again. )
You see, dogs live for "the Now" in time and space, rather than thinking like we do.
The gastro enteritis was a horrible thing for her to have to go through. I obviously can't say what caused it. Poor girl. Dear little Soul. Thank goodness that is over for her now.
Dogs do live on in Spirit. I discovered that from my own dear dog, and she still occasionally visits me from Spirit now, almost ten years later! Most unexpectedly she dropped in to communicate with me only last week. When she visits, it's a sudden sense of her character and energy, and tons of Love.
So what that shows me is that they still love us in a very deep way, are waiting for us for sure, and will never forget the lovely bonds that we share. They do not blame us for anything. They are happy to know us, happy for the life they shared with us. They just Love, and Love can't be destroyed by passing out of the physical body.