D.
It could be several things. Like you said, she tells you she's not tired. Well, maybe instead of "forcing" her to nap make her go to her room for quiet time. She has to close the door and look at a book or play quietly with toys but she has to be up there an hour at least. If she falls asleep, great, if not, oh well. It's also her testing her limits and what she can get away with. If she figures out how to get 15 mins out of you every night she has minipulated you into getting her way. I would keep bed time routine the same as it has always been. And she goes up whether she throws a fit or not. If you have to carry her up so be it. She needs to know that you are in charge here. If she continues to pitch a fit, let her. If she doesn't sit on the potty or brush her teeth, oh well. It's only one night. This is a phase, it will pass. But she's testing you, giving in sets the tone for her doing the same for other things as well. Because she will see that it worked for bed time so it will work other places too.