i know every child is unique but i also know that there are stages of development that most child go through. i wanna know if you have/had the same worries like i do?

at 15 months my toddler doesn't:
> know how to use his sippy cup. i tried to let him explore with it but still doesn't work
> know words except for mama, daddy, mumum (for milk), and that's just it. some of his words are plain sound of the letters T, B, D..... is this normal?
> pay much attention on object i describe. every single thing that interests him i give a description such as ball, book, toy, etc. but when i test him like "where's the ball" it seems he doesn't pay attention. or maybe he doesn;t remember. probably his memory is short. does this happen to you too?
> when he was a bit younger, i tell him to "kiss mommy" then he kisses me with his mouth open (lol) but know he's forgotten about that trick

what he does:
> what he sees, he does. like when i snap, he tries to snap his fingers too
> when i dance, he follows
> when he sees or hears my voice is angry/mad, he behaves and trying to figure out if i am serious or not. kinda cute but sometimes it's irritating lol
> he walks a lot but still wants to crawl a lot too.

please share you situations here