Potty Training-Still

I have been trying to potty train my 3 year old for I don't know how long. I am so through with diapers, but she's not. I decided to forget it and she would let me know when she is ready. I thought we were there. She even went to her grandma's in undies and kept them dry. Yesterday she wanted to wear diapers, maybe I shouldn't have let her but I don't want to force the issue. I thought she'd go back to undies after a day. Well, today she asked to wear diapers again. I told her that would be okay but I will not be buying any more diapers. I am going nuts though. I know she understands because she can stay dry if she wants to. ARRGGGG!