Weak bladder. Always having accidents

I have a 2 year old female ESS that has had a litter of puppies almost a year ago now. She is a runt and is on the small side. It seems like she is unable to hold her pee more than 5 hours. I work 11hours a day and come home to let her out during my lunch. Almost every time she has an accident in her kennel. Is there something with female ESS that can contribute to her having a weak/small bladder? What can we do to help prevent her having accidents? Any help would be great. Thanks