Rescued pup, needs help house breaking?

my husband and i just rescued a 6 mo. old female boxer puppy who has had a very rough first few months of life. She was seized from a high neglect home along with her sister, (same age). we adopted her from an agency and they said she was house trained, BUT shes not. she drinks an incredible amount of water if she is given it and seems to always be thirsty. We make sure to take her out at every possible opportunity as well as the normal, in the morning, after eating, after napping, after walking (am & pm) etc. etc. etc. we aren't yelling at her or her after peeing because she is a puppy and we know it can deter and confuse her. any help would be fantastic.. thank so much!