M.S.
Tell her not to worry! My 2.5 year old is healthy, but just doesn't gain weight. That's who he is. Is she super active? That could explain it. from year 1 to year 2 my son only gained 2 lbs and at 2.5 is currently the weight of most 1 year olds. I would say as long as she is eating well, is active, and growing even a little (height, weight), she should be good to go!