I'm concerned about my 17.5 month olds weight. She weighs 21 lbs. Her dr isn't concerned even though she's starting to fall off her growth curve. She's always been on the thinner side but now she is only gaining a few ounces in between checkups. She's a very picky eater but she does eat...A LOT. I just feel like she should weigh more at almost 1.5 years old