Have you ever considered giving her some melatonin to see if that will help regulate her sleep cycles? I personally have never used it but have read about quite a few people on this forum who do use it. It's completely natural.
Honestly, you're doing everything correctly. Given the fact that she doesn't have a prop and can fall asleep independently, she *shouldn't* be having as many issues with sleep as she is. As you've been trying to extend her A time, how much have you been trying to add? With touchy babies, some can only handle a 5min increase once per week. Touchy babies are *extremely* sensitive to A times.
With the night feedings, I would start extending the length of time between feeds during the night. Removing some calories from the night and adding them to her day might help some. When you do feed her at night, is she falling asleep on the feed? If so, this could be part of the problem. When she wakes, she doesn't know if you will feed her back to sleep or not so she just keeps waking. Almost like a prop, but not completely, if that makes sense. So, try to wake her a bit before laying her back in her crib after a night feed.