Hi, Sorry in advance for the long email. My twins are just 7 months old and I've been pretty successful at getting them to sleep through the night starting a little after 4 months -- but it was done in stages. Prior to that, I was an exhausted mess. I'll share ... maybe some of this will help you.
First, because I couldn't exclusively breastfeed, we were on the bottle. This was and continues to be helpful because I know exactly how much the girls are eating at each feeding. My pediatrician said that they should be drinking *a minimum* of 24 ounces of formula per day (we also are on solids since 4 mos). So, my first goal was to try to get them to eat as much of their 24 oz during the day rather than needing to eat it at night (in fact it varies from 25 - 30 oz bc we also mix formula w/rice cereal). Put some focus on this ... stick with her bottles when she pushes them away, give her a 10 min break and come back to it. The more she eats during the day, the less she *needs* to eat at night to catch up.
Also, maybe your daughter can't eat a lot in one bottle ... for a long time, one of my girls really preferred to eat more frequent, smaller meals (3 - 4 oz). She had a touchy stomach and too much food caused her to have an upset stomach / acid / spitting. So, if she only takes 3 oz consistently, try to give her another small bottle after 1.5 hours rather than 2 big bottles 3 hours apart. She may just have different preferences. It's more work, but it may get more food into her during the day.
When my girls dropped their first night feeding (2 am ish), it was a shock to me! This was a little after 4 mos. They woke up as usual, I went to warm their bottles and when I came back, one had fallen asleep again and the other was playing in her crib. So, I realized that they weren't necessarily waking anymore because they were hungry, but waking out of *habit*. From that night on, I did not feed them at that hour (remember, I knew how much food they were getting). My husband and I agreed that when we are driving in the car and can't get to the girls, they cry for a max of 20 - 25 mins before they get tired. We said that if we are ok with that in the car then we are ok with doing "CIO" for that long too. Honestly, the most my girls fussed after skipping that feeding was about 20 minutes.
Like everyone else here, we got into a bedtime routine as soon as we started to see a little eye rubbing between 630 - 7. Same music, same room, same small bottle. Seems to help. They go down between 7 - 8 pm with almost no exception. (We had issues with breaking some bad habits to get them to go down, but that is another email. :-) )
However, what I also do between 10 - 11 pm, is feed them another large bottle to tank up for the night. I keep the lights low, quietly get them out of their crib, don't talk to them, don't change them so they know that it's nighttime. After they eat whatever they are going to eat (anywhere from 2 - 6 oz), I quietly put them back.
Finally, just 2 weeks ago, they dropped their 5 am feeding. I don't know why or how, they just did it and now, even though they sometimes wake at that hour, I don't feed them; I just go in, give them their pacifier or whatever, and quietly go out... even if they fuss. Prior to that, I was giving them a mini-bottle of 3 oz to tide them over until their 8 / 9 am. It worked; it only took about 10 - 15 mins, and they'd go back to sleep and so would I!
A piece of advice given to me by another twin mom: "Don't go back." Once you drop a feeding one time or establish a good habit, don't revert to past behavior, no matter how hard. She found that it takes about 3 days to establish new habits.
A piece of advice from me that I read about: for feedings you are working on dropping, reduce the size of the bottle or the time of the breastfeeding little by little. As they get older, these feedings / wakings are often more habit than of need. So don't give them 6 oz bottles / 40 min feedings at 2 am. Reduce by an ounce or 10 minutes week by week, or after a few days. It is much easier to get up for 10 - 15 minute feedings than 40 minute feedings -- and it starts getting your baby in the habit of waking for less time.
Again, sorry for this ridiculously long email but hopefully some of this info can help. I know how tough it is when your otherwise perfect, wonderful baby is keeping you up at night. Feel free to send me a message if you have any questions on what I wrote. Hang in there!