L.A.
I used to do this a little when I was this age, mostly because I did not want to stop and go. I did not want to stop playing, I did not want to stop reading, I did not want to stop watching TV. I did not want to miss out on what was going on.
But her saying she just cannot pee, sounds like a physical deal.
Until you can take her to the doctor, set a times for every 15 minutes to make her stop and go. Let her know you are going to continue this to make sure she does not have accidents. My mom did this with me and it helped to realize it did not take that much time to go when I knew it was coming on.
She also had me rinse out my underpants after each accident.
Just let he know you are not mad, but concerned. It will help her not feel ashamed or guilty that this is going on. .