This rings bells with me as it reminds me strongly of my brother (now 53). We're convinced he is on the autistic spectrum/Aspergers. My mother had to make the decision to move into a small retirement flat to force him to be move out and become more independent when he was in his thirties.
He still suffers from extreme anxiety and some social difficulties. He worries about his job constantly, always convinced he isn't good enough (he works for a top company on IT projects and has a first class degree.) He is now married but his wife, although supportive, also has huge anxiety and health issues.
Geraldine I'm not sure whether a diagnosis of ASD (autistic spectrum disorder) would help your son, but background reading about ASD might help you understand him and his difficulties if he is on the spectrum.
The Republic of Ireland and their tensions with migrants.