This thread is both the most comforting thread I've ever read, and the most depressing! 
Clearly it's the right place for me though! My DD is 7.5 months old and has never slept well. There have been the occasional nights when she's only woken up a couple of times, but those are usually when I'm not there! (My Mum has had her overnight a couple of times to give me a break, plus DH has had her without me a few times). There was no 4 month sleep regression, she had nothing to regress from! Even when she was teething her sleep only seemed as broken as usual.
Generally she has no consistent pattern. Despite my best efforts she doesn't nap at the same time each day, and regardless of my 7pm bedtime routine she can fall asleep for the first time anytime between 8 and midnight. She's up and down all night long, usually hourly although tonight she's woken every time I've put her in her cot since 10pm 
She's always been clingy and sobs whenever she wakes and finds she's not being held. I think I mostly took it in my stride for the first 6 months. I just thought it was normal (even though all my rl friends' babies started sleeping through by 12 weeks
). I just thought she'd grow out of it. Plus she's my first child so I could just slob around in my pjs all day when the exhaustion got on top of me. Since 6 months though it's really starting to scare me, I'm terrified she won't sleep through for YEARS! DH has a cousin whose FIVE yo DS has always been a nightmare sleeper, and he STILL gets up a couple of times a night (even after a full day at school).
Sorry to be a killjoy, I know in the teeny tiny logical part of my brain that that is an incredibly rare and unhelpful story. It's just half midnight, I haven't slept yet, I haven't had more than 4 or 5 hours sleep in a night for a long time (and those hours are never consecutive). So I'm griping. Please forgive the long rant.
I'm up for trying some reverse psychology! Or a sedative, whatever works! 