Natalia - he definately understands what people say to him... I know for a fact that he can understand the meaning of fairly complex sentences we say to him.
However they did mention that when at daycare he doesnt follow instructions too well... but what 2 yr old does?

The other night was the first time I heard him put two words together - he said "more Dadda" (when they were playing rough and tumble)

His hearing also seems fine... he can hear us speaking softly to him... he can hear a car revving two streets away and will say 'carcar!' excitedly to me...

Tegan - I also thought it could have been the dummy, so he mostly only has it at night times now too.

I dont know if I should be worried or not... I dont really think he's intellectually behind others his age at all.
But I wonder if I should just stop stressing about him not speaking as much as others his age and let him take his time. Or if I should be worried and seek a professional opinion.

ETA: the more I think about it, the more words I realise he has... have just added another 5 to his list.