Re: I need some outside perspective
I think both. You are possibly reading more into the situation than is there and you are being realistic.
If you didn't have the other two children, I would say #3 sounds very typical. My nerotypical dd1 didn't wave, talk or point at that age. She didn't really love books until she was a fair bit older.
What is your household like - I wonder if he would rather be in your lap because he find the goings on of his older siblings just a bit too much to handle?