Reprogramming

We are once again in a sleep wasteland. We have been trying to get Callie to go to sleep earlier, in preparation for when I go back to work (if that does indeed come to fruition). As it is, she has been going to bed around 11pm. She usually sleeps 8 hours straight, but lately its been erratic. 6 hours one night, 7 hours another. So I figured it was time to try to move her bedtime back, since I knew I couldn't be going to bed at 11 during the school year and get up at 5 and still function in any kind of meaningful way.
I read through Healthy Sleep Habits Happy Child was fairly unimpressed. If you are interested in the science of sleep than the book is for you, if you are looking for an easy to implement system, its best you look elsewhere, in my opinion.
The first night she took a late nap, around 7 for a whopping 20 minutes. Like I've mentioned before, homegirl does not like to nap! Then we had some solid food, gave her a bath, read a couple of stories and off to bed. It took about an hour for her to go to sleep. Her screaming was excruciating. It was just like when we did sleep training the first time. Same drill. Let her cry for 15 minutes or so, go in a settle her down and repeat. Once she finally went to sleep she slept for 10 1/2 hours! Finally she was approaching the amount of sleep she was supposed to be getting. I thought "Ok! We got this!"
Last night we tried to do the same but she only slept 8 hours and is a mess today.
We will keep trying but it always feels like we are doing this part "wrong." I know she needs 10-12 hours of sleep at night and she just isn't getting it at night. It would be a different story if she would nap during the day, but she just doesn't.