Thanks so much for reassuring me ladies. He understands the difference between one and two things, maybe even three things, I'm not 100% sure. But he can definately tell more or less. He is interested in counting, he initiates it several times a day at the moment, when we're reading a book, going down the stairs, getting crackers out, doing stamping etc etc.

Ausgirl he gets most of the concepts you mentioned, big/small, boy/girl (but can't get his head around he/she yet), night/day, shapes and colours.... So, I guess that's a good sign.