Time for you to get help from a trainer. There are hundreds of articles online about potty training, and each one of them will remind you that it is YOUR responsibility to be sure your dog's needs are taken care of. When YOU do not do that, you can be sure that your young dog - whatever the breed - will make potty mistakes. This is normal dog behavior and has nothing to do with "dominance" - and everything to do with your lack of knowledge.
It should also be said that trying to punish a dog for what is YOUR mistake will only teach the dog that you are dangerous and unpredictable. No responsible person would ever try to "teach the dog a lesson" - because it's been shown that this kind of thing will not work. It's cruel to punish the dog for YOUR mistakes. Get help, stop hitting your dog, and learn a little bit about how to teach your dog - in a kind, clear, and sensible way, please. If this is inconvenient for you, then please surrender her to a rescue group - and don't get another dog.
http://dogstardaily.com/training/raising-puppy
"Your dog is a reflection of your abilities as a trainer." - Susan Garrett