Toils of toilets

So, i'm getting a little pushy about it, so what... I mean, i've had a very laissez-faire attitude towards potty training thus far, but with her third birthday rapidly approaching and absolutely NO sign of any interest in going pee or poop in the potty, I'm beginning to doubt my non-intrusive potty training methods. Don't get me wrong, she HAS peed in the potty. A handful of times. Starting around a year ago and then completely ceasing altogether. She peed in the potty to much raucous applause about two months ago, and since then not an inkling of interest.

She has cute Hello Kitty underpants that she has worn a handful of times, but she peed in them a couple times (after holding it for quite a long time and never wanting to use the potty) and since then has not even wanted to wear them. She has cute training pants and REALLY doesn't want to use those. I have offered her bribes - 3 stamps in a book for each poop in the potty and 1 stamp for each pee, upon collecting 20 stamps, she will get a roundhouse for her trains. The first time she poops in the potty, she will get a Diesel (one of the Thomas characters). She's super excited about the stuff, all of it, but absolutely does not want to pee or poop in the potty. She has not earned a single stamp.

How can someone who says, "I don't like it when you keep telling me that (about going to the potty) over and over again. It's starting to make me a little bit mad," NOT want to go in the potty. I don't get it.
I asked her, "Does that make you feel too pressured?"
"Yes, I'm not ready to go in the potty!"

Sheesh.