Never take advice from pediatrician
My best advice is never take breast feeding advice from your pediatrician. I have found that most pediatricians are totally ignorant to the workings of breast feeding and the development of a breast fed baby. When I worked for WIC I can't tell you how many moms I had go to formula because the pediatrician said baby wasn't gaining "enough" weight. Even had 1 tell me that I had to put baby on formula at 6 months because breast milk has no nutrition.