I am interested to hear how well other 2 yr olds can talk?...

Aidyn is 25 months, and I know he is behind in his speech.
His daycare haven't moved him up yet to the next group because he never speaks to them at all. Yet kids that are 6 months younger than him have been moved up.
I'm happy for him to stay where he is actually, because I know he is comfortable and secure in the group environment that he's in, so thats no issue with me.
But I wonder just how far behind in his speech he really is, and if I should be seeking a professional opinion, and how do I go about getting one?

He has a few words around 20 but most of them are said incorrectly (usually with extra syllables on the end)
He can say:
Mama
Dadda/Daddy
gawga (water)
kircle (circle)
carcar (car)
baw (ball)
butuba (butterfly)
be (bee)
go
bapple (apple)
nanana (banana)
moomoon (moon)
ka (cat)
bo (boat)
wowower (flower)
boon (balloon)
more
poo-poo
bye-bye
bah (bus)
dep (step)

and then he has noises for other words like train and dummy which I cant even translate here...

Does this sound normal, or do other people's 2 yr old speak much more than this?

Oh, and he doesnt even say 'yes' or 'no'....