There are some mums who don't tell the full truth or bend the truth about "sleeping though". There have been some cases where they claim sleeping through, but what they mean is "bubs wakes, but I don't go to them" or they are using some not nice things to keep their baby asleep. Now I am not at all saying that any of these other mums you talk to do any of that, but something to keep in mind so you don't beat yourself up over it.
That's so true! A friend of mine always insisted that her DS 'slept through for 12 hours' from 6 weeks of age. It turned out that they couldn't hear him at night from their room and they didn't have a monitor

What about dinner, then a bottle just before going to bed? Certainly can't hurt trying new things.
Some babies/kids don't 'need' to sleep 12 hours straight over night. When she wakes in the mornings, is she happy? Has she had enough sleep? DD1 needs to sleep on average 14 hours overnight. She has never been up before 6.30am! But DD2 has never slept past 7am, and doesn't get any where near 14 hours solid sleep. She just doesn't need it.
I know it's hard when you hear of other babies the same age sleeping all night. You start questioning yourself as a mother. That you must be doing something wrong if your child isn't sleeping like that. But just remember that not all babies are the same. Yes, it's hard at the moment for you, but it won't be like this forever.