Wits End

This has taken me 4 years.I have had concerns about my son for that long,but up until now I am still not sure if I am over reacting. My son is 12 now and he started displaying strange behaviour at age 8. It was mainly getting attached to certain words and noises and repeating them.However,he seemed to be doing it because he thought they were funny. Almost like a private joke. At this time he also started having noticeable problems managing emotions. Having extreme tantrum,crying and throwing things.These would sometimes be about not getting his own way,but would mostly be if things didn't go to his/our plan. We started having issues with his bedtime also, where he would be super silly before bed being attention seeking and procrastinate to the point we would have to shout. At this time he had some trouble with friendships. 4 years on and we have worked hard on managing his emotions and we have less issues with this side of things,bedtime is sorted and everything is definitely more settled. It is the noises and word obsessions that have continued.I would say over the last 4 years we have had obsessions with 15 words and noises. As before he seems to do it in humour thinking he is being funny.If he sees that you disapprove it just makes him be sillier to the point I end up losing it.I would say that his 5 year old brother has better control of himself. His relationship with his younger brother is mixed. He spends most of his time trying to do things to irritate him,which I think is normal,but he seems to take it really far and gets pleasure out of upsetting him.  His Dad used to toy fight with him when he was younger,but had to stop doing it as he would never know when to stop. He is doing fabulous at school,no concerns whatsoever.He has a group of friends,but is not very close to anyone.Gives eye contact and when he is being himself is a lovely caring lad. But I am worried these behaviours are our fault in some way as his dad worries about silly things and I used to be a bit of a shouter. Or I guess the reason i am here is I am worried there is something else I am missing. He is just generally more challenging than my other children and I am Ok with that,and I know we are in the midst of teenage hormones which I can handle.It's the repetitive behaviours I don't understand.He controls himself at school just don't understand why not at home.I am at my wits end.PS Hope I am posting this in the right place.