My 16 month old son-sensory disorder or autism?

Well I will try to make this as short as possible. we noticed at 12 months something just wasn't right. He is 16 mos. now and does not point, wave bye bye, say any words etc. He does on the other hand interact with us. He will smile, makes excellent eye contact, etc. he does not play correctly with toys, and he will not play with a toy with us, he will take the toy and hoard it from us. he also hoards dirty dishes and laundry and if we try to take anything off of him he freaks out!

He has terribly violent tantrums and has all his life. he used to say mmmm good and kitty kitty but he just stopped saying it about 7 months ago. He cannot tell us what he wants, does not listen to basic command such as pick up the ball or NO. He only responds to his name sometimes. when he is tantruming he acts as if he wants us to pick him up but then he pushes off of us and goes right back down. he arches his back,rubs his head on the carpet and will bang the BACK of his head off of things.

He hates socks but we are slowly weaning them on him. When he is tantruming, we cannot soothe him at all and he will start pulling at the elastic on his pants. he also prefers long sleeves and will hold them in his hands and rub them. He has many other quirks as well, but these are the main ones i can think of right now. He does not like to be cuddled, knows how to kiss but will rarely do it. He currently gets speech and occupational therapy. He also is TERRIBLE with transitions. Thanks!