N.C.
Hey! I am going though the same thing, in fact, while I am writing this my daughter just walked into the bathroom, went pee, and walked back to her room. :-)
What's really working for us is letting her sit up in bed and look at 3 or four books for about 20 minutes, then we come in, take them, and tell her good night. Usually, that works well, but every once in awhile she pulls the potty thing. I tell her fine, just tell me when you are done. I let her sit there and refuse to go in there with her. Yes, the first three or four times she sat there for almost an hour, but because I didn't make a fuss out of it she now will just go and walk back into her room and lay down. This process took about two weeks, but really works for my daughter. I understand the frustration though.
Hopefully this, or something will work for her soon! IT drives ya batty! Good luck!
N.