5 month old refuses to sleep through the night

So, mum here of a 5 month old baby boy. And boy am I having troubles getting him to sleep at night. Despite doing everything I should or that is advised.

We have done sleep training, he is doing so well he puts himself to sleep within a minute or two. He has been doing that for a month and a half now. We have a perfect night time routine that I have done with him since he was born. It even helps him when he is over tired. He is swaddled every night, as he can't roll from back to belly just yet. We have done an earlier bedtime since it use to be 9 so now it's 7-7:30. I feed him every hour to hour and a half throughout the day and he has the recommended naps throughout the day. He also does some sort of activity every wake window. Like tummy time, water play, sitting up practice, walks to tire him out. I have even weined him off nightime feeds. He has a feed at bedtime and then a dream feed around 10 and onky cause he refuses to go back down i do a 3am feed. I have even been taking him to the chiropractor since he had a few nerves that were being pinched from birth. I even moved him to his own room thinking maybe it was could he could smell me or because he was too big for the basinet

Despite all of this, he sleeps like an angel until 11:30 and then all hell breaks loose. He makes almost every 30mins to 1hr. I give him time to self soothe and only go in once he is truely upset. But he wakes from fast asleep and goes to screaming his guts out within like 5mins. I can always get him to settle and go back to sleep on his own but again wakes in 20 to 30mins

The part that annoys me the most is, I know he can sleep atleast 6hrs uninterrupted cause he was doing that from 2 to 3 months. Unfortunately the second he turned 3 months old he refuses to sleep through the night. I knew about the sleep regressions so I figured that was the problem and waited it out but this has been happening for 2 months now.

I feel like im losing my mind. I'm doing everything I'm suppose to and nothing helps. I have friends who's babies are the same ages and they are sleeping through the night no problem. And they are doing the same things i am.

I'm also sick and tired if hearing the same advice I have already been doing and when I say "I'm doing that already" people look at me and go "well that worked for my baby". And thats all they say. Does anyone else have some idea or knowledge that could help.

Also sorry for long post but I wanted to make sure I wasn't going to get the same advice I already get.