@Drepess Thank-you 
Fucket, if you have other children and you parent them all the same and the others don't behave like your son does, then it's not your parenting that should be in question.
Whilst you're waiting for some help as currently your son is masking, (there may be a point when he can't then all the people who "don't see" anything will suddenly see and at least recognise there's difficulties) do read as much as you can about different AN and what techniques can help, then just use a system of trial and error until you find things that work, it doesn't matter what AN the techniques are specifically for, if they work for you both, they work.
Here are a few ideas based on what you've said, feel free to take anything on board that you think may help and ignore the rest, you know your child and what he'll respond favourably to. I could be way off the mark.
Noise, will he wear ear defenders or noise cancelling headphones? Can you warn him in advance about any noise the family are about to make?
Does a spiky wobble cushion help him to sit still and focus?
Is he calmer with a weighted vest or lap pad?
If he's hyper would a mini trampoline be an option?
Anxiety can be the driver for a lot of behaviour, if you can find what causes the anxiety and reduce that, the behaviour shouldn't be so extreme.
Re visitors, can you do a first, next and then explanation about what's happening and explain to him what his role is in that situation.
It sounds as though he's seeing his safe space being invaded and doesn't know how to cope and he's frankly terrified because he doesn't know what's going on, he doesn't know why those people are there, everyone else seems to know what to do and how to act while they are there, but he doesn't. For him, home has suddenly become very different with different people in it and he doesn't know what to do to make it like home again. He's overwhelmed.
All behaviour is communication, it's just figuring out what's being communicated that's the hard bit.
Also he may not pick up on any inferences and be very literal, try and modify explanations and communication to simple, clear instructions.
Re transitions, a now, next and then explanation can help change from one activity to another so he can understand why one thing has to stop and another one start.
Other sensory stuff www.falkirk.gov.uk/services/social-care/disabilities/docs/young-people/Making%20Sense%20of%20Sensory%20Behaviour.pdf?v=201507131117