Hi!--I feel for you. My son didn't sleep through the night until he was 7 months. It was a long process for us, but the book that helped me most was "Healthy Sleep Habits, Happy Child." I joked that it should be called "Happy Sleep Habits, Happy Mommy!" It's by Marc Weissbluth. He talks about several options for getting the baby to sleep, and the pros and cons of each. By the time I was crazy exhausted, I chose to use the "extinction" method--basically letting my son cry through the night to learn to go to sleep. It was not a pleasant experience for us, and I questioned myself every time, but ultimately, I knew that it would work (and it did!). I chose this method over others because I knew that I didn't have the energy anymore to be consistent with the other methods. Also, I knew my son would get more upset and worked up if he saw me midway through the crying it out process. If you don't want to let your daughter cry-it-out, another good book is the "No Cry Sleep Solution."
Both of them stress consistency. From the Healthy Sleep book, one of the most helpful pieces of advice that I got was making an early bedtime (like 7pm). Most babies get over tired if we push their bedtime too late, and then have a harder time falling asleep. Try making her bedtime early, and then keeping the bedtime and the routine consistent. For me, that meant 6:30 was bath time, then pjs, reading books, and rocking while nursing, then to the crib. I patted his back a few times and then walked out. It took my son a month to get to where he'd sleep straight from 7 until 5:00am. Some would say that since it took him so long that he wasn't "ready" to learn to sleep, but I knew I was at the point where I needed him to sleep, so that's the way we went. As a single mom, you need to take care of yourself as well as your baby, and that means that most times you give in to your baby's needs, but sometimes your needs come first, and your baby will learn to adjust as well.
There were also good tips for making a consistent nap schedule during the day which helps with the overall sleep patterns too. My son is now 17 months, and has been getting a solid 10 hours sleep nearly every night for the last 10 months. And I'm getting sleep now too, which makes all the difference for our days!
Good luck! Try those books, and hang in there!