Please listen to your doctor. Your daughter is getting plenty of water from the breast and baby food if you've introduced it yet. If you are worried, you could always us your intake of water. I copied this from the Cinncinatti Children's Hospital Website.
CINCINNATI -- Water may be essential for children, adolescents and adults to keep hydrated in the summer heat, but for infants, too much water can be life-threatening.
"Breast milk or formula is the only source of nutrition that infants need," says Michael Farrell, M.D., a gastroenterologist and chief of staff at Children's Hospital Medical Center of Cincinnati. "During the first months of life, too much water can upset the electrolyte balance, setting off possible brain swelling and seizures from water intoxication."
In addition, too much water can fill infants' stomachs so they don't get the nutrients they need to grow. This is particularly common in families that cannot afford formula or may dilute it to make it last longer.
Dr. Farrell suggests avoiding water entirely until a child is about 6 months old. If an infant has diarrhea and vomiting, he suggests oral rehydration fluids, such as Pedialyte" or Infalyte".