how old is your dog? puppies cant hold that much in. I would bring my dog outside when he woke up, finished playing, basically moved or every half hour he was awake. If you are trying to solve the problem of how she can notify you, give her a bell to ring by the door Training Your Dog to Ring a Bell to Go Out to Potty
If you dont want to do a bell, follow the same rules by having a designated spot you have her go to before she is allowed out.
Catching her in the act you should not scare her, she will get a complex about peeing and she will be afraid to ask you to go out because she thinks she will get a big noise that scares her. Just pick her up and bring her right outside and when she finished praise and love even a favorite toy or treat. Does that make sense? Not sure how big she is. Anytime your eyes are not on her 100% of the time she needs to be crated so you can monitor her bathroom breaks and don't give her a chance to go pee because you are always watching her close. Is she crated overnight and holds it ok? How does she do in it?