Concerned for 21yr old Son who's possibly on the Autistic Spectrum

[MelloOneMelloMe]

Hi, hoping to get some feedback and support regarding my current situation with my 21 year old Son. Who I have long suspected is on the Autistic Spectrum or possibly has some kind of oppositional disorder. Maybe PDA.
His Dad, my partner has been diagnosed with aspergers syndrome.
We once took our Son as a 6 yr old to a behavioural specialist (at the request of his school) who saw him for ten mins, made him play with some toys and said there was nothing wrong with him!

My Son has always been difficult as a boy. Running out randomly into the road as a 3 year old to kick a can or anything. That didn't stop until he was about 7 or 8.
Not listening to what he was told. Argumentative and lacking a complete awareness of household hierarchy. Teachers made him sit at the front of the class for years to control his distractibility.

But, once he hit his teenage years. It became a constant battle of wills. He was suspended after only a week at secondary school for thieving...because other people told him too! He was considered a high achiever at school. But has been thrown out of every positive extra curricular activity they've invited him to partake in. I was called up and down his school, and sixth form on countless occasions to discuss his 'inability' to listen, or follow rules and school boundaries.
They gave him chances after chances, as in contrast he was mild mannered, highly articulate and academic.

He only lasted less than four days in his work experience, before they asked him to leave for not following instructions. And sitting during working hrs in the canteen playing on the handheld console he'd stolen from his sister.
Push came to shove during his A levels, and he was asked to leave countless subjects. But he just tried other subjects and took retakes.
However, I did have many phonecalls and had to attend meetings with teachers about his behaviours. Again not following their rules about lesson times, rudely walking in mid lesson. Not completing the work and oblivious to the teachers pleas and my own.
He's stolen mine and his Dad's money, and belongings countless times. And then just leaves the stolen items blatantly laying on his bed in his room!
It's like he thinks he has to follow no rules of respect or of personal boundaries.

His rudeness knows no bounds. He's always had n issue with blunt comments and rudeness. But, more recently began swearing at me. Calling me names, and being disrespectful. He won't look me in the eye when I talk to him about his behaviours, preferring to look at the wall. This started as a child and has remained.

Miraculously, he managed to pass his A levels on his second retake of his year. Then went off to University aged 19 to live on campus in another city.
Whilst there we barely heard from him, and he avoided all calls or texts to see how he was doing. But, we also enjoyed what was now a more peaceful home.

Then it all went wrong for him last year.
He failed his first year at uni, and was told he was not allowed to study their anymore. He ended up back at home. He lied at first and had us believe he was going back to uni all summer!
It seems he'd come home worse than ever. He's now developed extreme anger alongside everything else. And we had three separate occasions where he became aggressive, because he felt we were asking too much of him. Asking him to pay his way as the young adult he is.
I even had to call the police a few months ago, as he started chucking a kitchen chair around, and threatened me and scared his teen Sister. The rage in his eyes was scary.

He hates people telling him anything. And misconstrues peoples intentions. He's had three part time jobs in recent months and just walked out on them all. I even had his manager call me up saying she was worried about him. As he'd not turned up to work for days, and he always seemed so polite to them. He has a very calm manner and like I said highly articulate. So, people are shocked by his sudden lack of responsibility.

As you can imagine its been a complete strain. I am not in the best of health. I have anxiety that is now at it's worst. And my Partner has his own set of health issues himself, as well his aspergers. We have a teen Daughter who's witnessed and endured her brothers behaviours alongside us.

It all culminated in him flipping out 2 months ago, and smashing up some cups, bowls. Then when we asked him to leave, he packed up a bag of clothes. Then as he left he smashed up our front door light, doorbell and threw our food bin over the hedge!

Since then he's been hiding out at his Dad's parents house for two months. Living there for free, and even a transport fare fine he accumulated whilst staying there, he's had them pay it! He owes a lot of money, inc his student loan and another loan from somewhere else.
They are not healthy people, and of retirement age. As far as I can see we are also being blamed by my partners parents, because they no longer talking to us, and our Daughter.. I don't know what he's told them. But they don't appear to be interested in our story. That's been a added stress.

It's actually a mess. And ive spent a lot of time feeling upset, angry and relief that he's not here.
I feel he's undiagnosed and not about to be put straight by his paternal grandparents. My partners mother has never been interested in her own son's asperger diagnoses. And even blamed the Doctors for supposedly dropping her Son on his head when he was born!

My Son has said in the past that he feels he is 'different'. But that it isn't autism...and we all misunderstand him. He has on occasion said PDA fits. But then a week later he accuses me of telling him he's just like his Dad!

I worry for my Son's future. He's a man, I know I can't force him to get help, but then I am his Mum still. A mother never stops caring.
And I'm just looking for some words of encouragement and support from people.