What a terrific question, thank you!
There’s an interesting biological mechanism that means you can’t pee when you’re incredibly close to cumming (more powerful in men than women but tends to work in both). You can use this in terms of getting a full bladder and then edging yourself on a toilet and discovering you simply can’t pee even when you try, which can be quite a mind fuck.
If you can pee while close to the edge, try sitting on the toilet in a pair of panties, and peeing through them, it’s a really unique sensation as they saturate and you feel it spread everywhere.
I’d be interested for you to try just drinking lots of water over a few hours until you’re desperate and simply edging until you wet yourself, at which point you have to stop playing for the rest of the day – an incentive to keep it in as long as possible.
Something very effective can be to place a vibe between your pussy lips and press yourself against some furniture or the edge of the bed, with a full bladder, so the vibe makes you edge but the pressure makes the pee holding very intense. Try not to make too much of a mess. Good girl.