Goodness, you poor thing, you must be completely running on empty! Since you sound like you've tried lots of things I don't want to offer any advice, I'm sure you've heard it all, but I didn't want to read and run, just wanted to offer a virtual hug

(and say welcome to OHbaby!). Sleep seems to wax and wane here, sometimes it's good, sometimes it's awful, I think lots of us have that experience

but unfortunately it does seem that some babies need less sleep. (Although every hour or two at night suggests that he might just be trapped in a cycle of overtiredness

)
Actually, I do have some advice - might be a good idea to email Louise at The Sleepstore? They're the experts on the subject and she might have some ideas that you haven't tried...