G.B.
Was the Dr worried about her size and lack of growth? If she is still going upward on the chart then she is growing at her own pace.
I have a preemie son who is now 6, he is small for his age but there is actually a couple of kids who are smaller than he(they are very tiny for their age) He was always below 3% on the charts but the doc would say he's growing slowly but still growing so not to be concerned. We did give him the weight loss shakes for a while to help him gain weight. But, if the doc didn't suggest a problem or a need for alarm then I would just try to keep her eating healthy so you know getting the right nutrients.