R.
Please try to remember the charts the Dr's office uses are guidelines...
When my oldest was young and we visited the Pediatrician, they acted like I kept the child in a closet and only took it out to feed once a day. She was always way below the the "norm" in weight while being extra long for her age despite a healthy appetite and 100% breastfed. She is now 22, taller than me, never had a fat day in her life and could be a Victoria Secret model. And healthy as a horse. Still can eat anything she wants without weight gain. While it is important to track weight gain, overall health of a child, physically and developementally, don't allow the medical community to make you feel like you are "being a bad mother". Each child is different.