My breastfed toddler (14 months) hasn't gained any weight in a month and a half. The doctor was a little concerned. I forgot to ask which growth chart they were using. I honestly don't even know if there is a difference in the charts after a year. He's 21 lbs. We're going back in 3 weeks to get weighed again. Should I be worried? About 75% of his calories come from my milk. He just won't eat more solids. But I can't imagine that being the problem since there are more calories in milk. Any advice?