Dude, just ask her if she wants to see what she paid for. She sounds like she would be up for it. If anything sexy happens, it happens. If not, youhave still had the thrill of your mum seeing your "ball willy".
Wetting annoys the hell out of me. You're a big girl, at least pull your pants down to pee. And Diapers. Just... Why? Acting like a baby is not a turn on for me.