4yr old son

I'm pretty sure there is something "wrong " with my son. From day 1 I thought there way. He used to twist his hands constantly, from 4 weeks old until he could walk around 2. He never looked at us, never sat up until 10 months, walked at 2, commando crawled at 14 months.
He learnt a few words then "forgot" them, and became mute. Ended up in speech therapy and learnt sign language. He finally started around 3ish. But unclear. He became!w angry easy because we couldn't understand him.

And now he's nearly 5, he is so angry, frustrated and emotional! We can't talk to him normally because he can not understand how to have a conversation, he talks over us, gets upset if we don't "listen" repeats constantly what's he's saying even though we are trying to answer him! He cries if we look at him, if we try and play with him ect. He proper sobs sometimes, over stuff like me talking to someone and not answering him straight away!

He smacks me, kicks me, threatens to hit me a lot. He slams doors, screams full pitch if we tell him no, not like a normal child sulking because he's been told off!

I just don't know what to do, he's so loving when he wants yp be.

Hi, I'll start by telling you who I am. I work in a county program for autism and have joyfully worked along sides of people who have autism for the last 5 years and it has become a passion I know will last my entire life.. That being said. Here's my two cents...
Music therapy. Find someone who can provide music therapy. It's the most amazing thing you will ever see (at least it was for me) something about beats and rthyms of music helps a person with autism organize, thoughts, speech and motor movements. And helping to organize these necessary movementa and such can help your child not feel so angry. Think about how much of a relief it would be to be able to make your body do what you want it to do.
Also, are you hooked up with any county programs? Speech therapists and such are good but ask for a communication device, communication is key for both of you.
I work with a nonverbal very sensory based young boy and before he had his device he would cry and wail for hours until he had the opportunity and right support to help him communicate. Even if it was just being able to say he was mad. And time he was out of control and upset I would use his device and open the emotions category and ask how do you feel? Even though I knew he was upset it was still a total complete relief for him to be able to say It for himself I am mad. I am sick. I am sad. Ect.
What sort of resources do you have for autism support?

Hello happypenguin2014,

My cousin's 5 years is on Autism Spectrum. There are plenty of resources and support group available.
If you are in USA you can check out http://www.Autismenabled.com. My cousin found out great products to help her son. Their products and services are good. Never had a problem finding the right product and getting it delivered. Like-
Calming- http://www.autismenabled.com/c-879-calming.html
Sensory Motor- http://www.autismenabled.com/c-1215-sensory-motor.html
Motor Skills- http://www.autismenabled.com/c-458-motor-skills.html

On holidays I usually give Gonge products as presents. He loves it- http://www.autismenabled.com/c-1546-gonge.html