I'm 63 years old and my appetite has diminished tremendously from when I was in my 30's, 40's, and even 50's. The older we get, we lose our appetite and the need for food all the time.
Let the dog drive when she's hungry. If she's not hungry in the AM, don't force her to eat anything. She'll be hungry enough in the afternoon or evening, she'll be fine then.
We leave dry dog food out 24x7 for our 2 weiner dogs. They nibble all day, one nugget at a time. Never worry about them. They can feed themselves. But they sure do beg when WE eat!