Hi Mary,
This may or may not be normal for your dog. Several things to consider are the type of food, calorie content, and nutrient profile of the food. These factors may limit how much she wants to eat. Alternatively, there could be a medical reason such as dental disease, intestinal disorders, endocrine disease, or behavioral/stress problems. If you haven’t had a recent checkup with your veterinarian, I would encourage you to do so.
I hope this helps!
Dr. Ryan Llera