16 month old son not talking, walking, or pointing.?

I have a 16 month old that doesn't walk, talk or point to objects. He walks on his toes mostly and stand up only against furniture. I've tried to get him to walk, but he refuses. He goes right down and crawls. It seems like he has no interest in walking. He also is not talking. Everyday I tell him mommy, daddy, baby, simple words and he just looks at me and either laughs or ignores me. All he does is moan, but it's not a pain moan. Pointing is another thing. He doesn't do that at all. I point to things and ask him if he wants it and he will just look at it and moan. That's his way of saying I want it. I have a three year old daughter who at his age was holding conversations with me. I don't like to compare my daughter to my son, but I'm really getting scared now. Everyone keeps telling me don't worry, he'll walk and talk when he's ready, but he's 16 months old and doesn't do anything. He's never been sick since he was born, he's very healthy, he eats very good, in fact, he's above average in that area. He doesn't use a pacifier and his hearing was checked and it's fine. Has anyone had this problem before? What should I do? Am I overreacting?