God bless you...I have been working with children with disabilities for about 12 years and toilet training is one of the most difficult things to teach, but here goes my 2 cents
There are a lot of great books on toilet training out there, and most of them are variations of "Toilet Training in Less than a Day" by Foxx and Azrin. (Even Dr Phil used their methods) It was written in the 70's, so it seems a bit harsh in 2008, but at the time, it was revolutionary. Basically, it's about teaching the child to recognize their own cues (that"gotta go feeling" in other words) and it seems like you're already doing most of that...
The couple of pieces you may be missing are Dry Pants Inspections and a routine for changing. Dry Pants Inspections, I find, make a big difference. Every 15 minutes (then you can make it longer as she does better), ask if she's dry. When she reports she is, praise like crazy..try and make this the focus of your excitement about her toilet training...still praise for going on toilet, but beef it up for staying dry.
Also, when changing her, keep it as quiet and businesslike as possible. Have her do most of the work, including cleaning up (you can use safe cleaners and paper towels). Keep the conversation to a minimum and keep your tone of voice neutral. This shouldn't set the occasional for discussion.
I have never found any success toilet training a kid in pull-ups. Toilet training is a drag when you have to stop fun things and go to the bathroom...most kids will pee in the pull-up given the choice..they feel too much like diapers and, let's face it, kids know what diapers are for!
Most important, stick to it...trust yourself, trust her, and trust that you are doing the right thing...Toilet training sucks for everyone involved but you'll get through it! Deep breaths, glass of wine when she goes to bed, etc!
Hope that helps! Good luck
A.