Hi , my Boy is 21 months old but he is still not speaking in sentences or has a wide vocabulary. I read he should acquire more than 50 vocabulary but his is still very limited. Words that he can say: Ma Ma , dad, ge ge (Brother in mandarin) , clock , eggs , bus, ball, meow, nose, eyes, what's this , I don't want , no, Yi Yi (aunt), po po (grandma ) .. I think that's about it .. should I be worried ? My friend's kids are all speaking with much more vocabulary than my boy so I'm very worried. My elder son was already speaking in sentences when he was 18 months old .. I don't wanna compare but can't help but get worried:(