T.S.
Nighttime dryness is physiological not an issue of will. The "training" goes in the opposite direction from day training. Sadly, no amount of praise for staying try, cute panties, or wanting to be a big girl will keep her dry in her sleep until she's ready. She can't stay dry at night just because she WANTS to. You honestly should have waited until she was consistently waking up dry to ditch the pull up. There's nothing to "try again when she's older" you need to wait until she is ALREADY dry through the night, and stop using a diaper/pullup at night when they are not needed.
How about picking up some cloth trainers (they sell Charlie Banana cloth diapers and trainers at Target now)... not the Gerber thick panties, but cloth that really can hold pee and has a waterproof outer. They can just be "nighttime panties." She'll feel a little wet if she pees, but it won't make a mess. (Even if it doesn't bother you to change the sheets, you don't want her to be the kid who smells like pee because she laid in it and it got in her hair and you didn't have time to wash it... :-/ )
Hope this helps,
T.