My dd is exactly the same, and I've just come on here looking for help and found this thread.
She was three last week, and has been in pants for over a year. She's always had amazing bladder control and could wee on demand, she never did whole wees everywhere, we'd just notice the wet patch where a little had leaked out and she held the rest in. About 6 months in (don't laugh...) we spent about 2 1/2 weeks giving prizes for every wee where she had dry pants. The incentive of a chocolate, or a little toy like a finger puppet, and mummy dancing up and down was what finally got her to put down her toys and go for a wee when she needed one, and having got in the habit, when the prizes ran out she continued to take herself to the loo. Result.
She was dry for months, then in January started with the wet patches again and here we are three months later.
I know she knows she needs to go, she knows how, she knows where, she knows she can go by herself or ask me to go with her, she knows I'll be encouraging and excited if she's gone. If I ask, the answer is always 'no' even if her legs are crossed and she's doing the wee dance! She has never ever cared about being wet or dirty, she just can't be bothered. Going back to nappies would be a reward for her - then she wouldn't have to bother at all! Most days she can by dry by me saying 'we're going out so please see if there's a sneaky wee' or 'please go for a wee and wash your hands before dinner'. But this afternoon we were just playing at home and she did several wees. I was in floods of tears when dh got home
Sorry didn't mean to hijak or ramble quite to that extent, I'm actually encouraged that I'm not the only one going through this!