Don’t know what to do

I actually feel like I can’t do it anymore, my son does not listen to me at all and as the weeks gone on it’s just getting worse. I try and be patient, calm and of course I tell him very sternly. He just refuses to do everything I say and it’s got to the point where I am at a loss on what to do. I’ve done every technique possible and spoken to HV but feel like no one is listening. Finding this age so hard and feel like everything is my fault.