I have a 4 year old with similar issues and I feel the same way!! I have my own therapist, and she reminds me that it is part of the age. Part of it is just how the brain works - brain growth is huge in the younger years, so you have new synapses forming and all sorts of stuff going on in the brain.
Sounds like you are doing all the right things, and for her it just may take longer. Love and Logic is good, so is a book that I read called "Whale Done"
It is important to remember that if you don't follow through all of the time, it will get worse. Studies in behavioral conditioning has shown that. So even when it is horrible and you feel like strangling her, and you want to give in, remember that it will pass, and she will be happy again soon.