You have a fantastic thing going here and if you push it, you're going to lose it, and possibly her altogether. You don't find a lot of girls willing to wear, never mind wear during sex, nevermind wear during sex AND pee in them. You need to take what you have an be happy for it. Take good care of her, she clearly accepts you for who you are, and as long as you are good to her, she'll keep wearing for you.