Many two year olds are like this. They need constant closeness. You did a good job of having him feel deserving and bonded. I would just try to involve him in activities side by side with you and otherwise keep responding and enjoy it.

But, having a baby so soon with such a high need child is going to take some learning. There is a great set of CDs I highly recommend. It is called Babies and Toddlers, to Tame or to Trust. It is a recording of a class with issues of babies and toddlers, jealousy, and other wonderful stuff you will need.
AuthentiParent.com has it too.