A.,
I hate to sound blunt or harsh, but please know that I want to help you, so I'm going to give it to you straight. The issue is not your baby's stubborness, it's your lack of consistency. It sounds like she's a smart cookie and knows that if she screams hard enough and long enough, you will eventually give her what she wants. Every time you let her cry it out and then give in and get her out of bed, you are reinforcing to her that it was worth it to scream that long. If let her cry for 45 min the first time and then get her up, the next time she'll scream for 50 min. When you let her cry for 50 min and then get her up, the next time she'll scream for an hour. It's your waffling that is making the situation worse. If you want to sleep, you've got to be willing to break the cycle. If you don't think that you can handle following through on the technique that I'm going to suggest, then PLEASE stop letting her "cry it out" at all until you are ready to fight this battle, because you really are making it more difficult for the future by sending her mixed messages.
So, here it is. It's a VERY simple plan that is VERY effective if you are VERY consistent. You go through your normal bedtime routine, hold her until she is sleepy but not asleep. You want her to know that she can soothe herself to sleep (and back to sleep if she wakes in the night), so it is essential that you NOT rock her to sleep. Lay her down with a lovey - a small stuffed animal or something she can hold. Don't worry about smothering - she's old enough to move something out of her way if she can't breathe. I'm assuming that she cries as soon as you put her down. Rub her head, give her the pacifier or her thumb, blow her a kiss and leave the room for 3 min. She'll scream her head off but DO NOT GO TO HER UNTIL TIME IS UP. Then go in, wipe her tears, rub her head, assure her that she's okay, but DO NOT PICK HER UP. Stay only a minute or minute and a half, then blow her a kiss and leave the room for 5 minutes. Repeat the above steps, each time lengthening the time outside of the room to 7 min, 9 min, 11 min, and so on, but the time inside the room is always 1 to 1 1/2 min. Each time you leave the room know that she is going to pull out all the stops - screaming, coughing to the point of making you think she is choking, and so on. You and your husband (if he's not on board, send him to another part of the house because you can't have him adding to the guilt that your child is already trying to lay on you) need to be strong, stay calm and reassure yourselves that you are not doing anything to endanger your child. You are not being cruel, you are not traumatizing your daughter, you are not going to undermine the bond that you have been building for the last nine months, and she is not going to starve to death. I have an eight month old who has been sleeping through the night since she was about 3 months old. She is very healthy, very happy, and we are very well bonded. I put her down when she is awake and most nights (and naps) she doesn't make a peep. If I do have to go in to comfort her, she never fusses past the 5 min check. My older daughter slept through the night at an early age as well, and the same is true.
You can do it! It's not only you that needs your sleep, it's also your daughter. It's up to you to teach her good sleeping habits, or she will always have difficulty. She does not need to be eating every three hours. Her stomach is big enough to hold food to last her through the night (do make sure you're giving her baby food in addition to the milk during the day). She is not getting up because she's hungry, but because she doesn't know how to get herself back to sleep, and it's a habit that she needs help breaking. When she wakes in the night, do not run into her room right away. Wait 3 min, go to check on her, and repeat the above process without picking her up or feeding her. It will be a difficult couple of nights, but if you are consistent and ride it ALL THE WAY OUT (do not give up after 45 min and say the system doesn't work) it should not take long to get her used to it. If my 8 month old wakes at all in the night now, she rolls back over and goes back to sleep on her own because we've taught her that she's capable of it. Your daughter is too!!
I have a friend that was in the same situation as you before I had my second child and I told her the same things I've shared with you. Her response was that I was blessed to have had an "easy" child and it was harder for her because her child had always been needy and cranky. Well, I'm here to tell you that my eight month old is a very stubborn child and has a much stronger personality than her older sister did at this age. The system still worked. When my friend stopped making excuses and was consistent, her child finally learned to sleep through the night too (only she waited until the child was 18 months old! Imagine how sleep deprived she was).
Good luck!
J.