So what do you think Autism is, then? The triad of impairments aren't "woolly and subjective"
How old is your son and how does he present day-to-day?
Do you think all he needs is a bit more discipline and everything will be fine?
Do you think you wife exaggerates and should be a better parent?
Do you realise a diagnosis of autism is done by usually a team of medical professionals, often after several appointments. It's not some fancy name that unqualified people tag onto kids for their own amusement.
Loads of fathers refuse to acknowledge their kids are different enough to even contemplate a diagnosis, so you may want to do some serious soul-searching and make absolutely sure it's not your own prejudices getting in the way of clear judgement.
Do a LOT of reading about Autism.
Look up the MChatR test and see if your son would have scored highly at the age it's designed for.
Look up the AQ test, do it and see what you score yourself.
Read this board and SN Chat over about 6 months or more if you can and see how hard most parents - usually mums - have to fight to even get a referral for their children, let alone a diagnosis. Read all the posts about fathers not wanting their kids to have a diagnosis.
Do all of that, then you may have some idea of what you can do to help your son.