Nowhere will ever have as much as London because the bottom line is London is a capital city and none of the other cities are.
You sound like you're thinking you can't ever bear to be in a not-capital city because you want only the very shiniest and best and classiest of everything, whether it's art galleries or streets or bars or whatever.
If that really is all you want, then you'll have to move back to London one way or another.
I think people are right when they say you're not trying though. Not everything is better in London - there will be individual bars, individual galleries, individual places to go that are better in Manchester than anywhere else - places you can discover for yourself if you make a mental commitment to where you are.
OK, being in London is a short cut to finding lots of good stuff easily, because it's the capital - but you can't live there right now. That doesn't mean you can't go down for weekends for treats. It's only four hours away on the train and it's still your capital city even if like most people in the UK you don't live in it.
Just do what everyone else does who is British but doesn't live in London - visit your capital city when you can to enjoy the sorts of cultural etc. things you can only see there, and the rest of the time entertain yourself with what's local to your home.
Do you also have a feeling of not being where the 'beautiful people' are, I wonder? Or are there specific friends from London who seem to look down on where you are now, by any chance?
All of London is still there for you. You just have to use it in a different way. You can do that while still enjoying what you've got in Manchester too.