My 20m old ds can say
bike
duck
a cat
a dog
ball
car
shoe
no
mum and mama
dada
nana
Marc (his uncle)
door
ta
all gone
oh no
uh oh
nunnite
nose
eye
flower
my dada
my mama
If you ask him where most thigs are body parts, food, toys(Thomas, noddy, ball etc), people and clothes he will get them or point to them. He understands allot more than he can say.
But up until 17 months he only had a vocab of 7 words. He will repeat or try to repeat most things if i say 'Can you say xxxxx?'
It is just as if a switch turns on and they just start to cotton on! Try not to worry too much. I just try to read to him and will ask him simple and normaly the same questions through out the day until they click, then move onto something new.
Also may sound barmy, but if you are at home alone talk through what you are doing.
Mummy is putting away the washing now.
Mummy is making lunch. This is the bread, do you want ham? Lets get the ham from the fridge. Its cold in the fridge. The butter's in there, we need that too. Etc.
You will feel really silly. But it can help with language in a big way!