This isn't really a reply to the question, rather, it's me agreeing with your problem. I'm having a similar battle with my daughter who is almost three and a half years old.
It's not about the potty, though, it's about the stalling. It's driving me CRAZY.
I have the bedtime routine, we do the bath, brush teeth, floss teeth, story, and turn out the lights. She gets a sticker for each activity and then a "prize" for doing the routine for three nights straight. (the prize is usually one of those coin-rides they have in front of the wal-mart).
Lately, I've noticed that she always wants one more thing. "Wait, wait, mommy...." and then mumbles something incoherent. Or it's water, or potty, or a hug, or one more thing she has to tell me. I always give her the warning, I tell her "OK, two more minutes and I'm leaving." She keeps begging me to stay then I have to get firm with her.
I don't yell but the tone of my voice definitely changes. As soon as she hears that, she starts crying. What happens then is she has a fit, runs to daddy, then calms down and makes nice with me and then I put her to bed. It's just now our routine is being stretched out longer and longer. I start at 7PM and by the time the whole ordeal is over, it's anywhere from 8:45 to 9PM. My patience is wearing thin.
She didn't again tonight. I just told her that I wasn't going to deal with her. Of course I felt horrible, but I don't know what else to do!