DD didn't sleep through until she was 10 months. Until then, I tried just about every trick just about any-body told me. I finally implemented Control Crying at 10 months and within 3 nights DD slept through (7am to 7pm).
I'm at two minds with this one. Some-times I think that its really upto the baby and nothing you can do will expediate them sleeping through. Then other times I think that DD would have slept through earlier if I didn't pander to her every whim and implemented a little bit of tough love.
Like you, I thought babies slept through from between 6-12 weeks. I remember when DD was 6 weeks waiting to see my GP and a mum with a 9 month old said that her baby still wakes 2-3 times a night. I never thought that would end up being me too !!!
I don't know how I coped looking back. I have to say, its scary thinking when (if) we have another baby, that I might have to go through that all again, but with at toddler to care for too !!!
DD is 3yr 8 months - DS is 6 months