At my wits end 
4yo ds has become increasingly naughty and does not listen to a thing I say. Today I have had to go to an appointment, it was humiliating and I don't know how to discipline him because he just laughs in my face or lashes out trying to hit me.
When he was aged 3 hv wanted to have him assessed for autism, when I moved the new hv team wanted him assessed for adhd, then changed their minds.
If I tell him off he laughs. I've tried the naughty step, he says he enjoys it, I've tried taking away toys, he's not bothered. I don't know what to do anymore
all the time his behaviour is becoming worse. He becomes aggressive when he gets himself worked up and I worry about taking him out anywhere now.
Any advice on how I should be dealing with this?