Are there any animal shelters in your area who might help with a vet ?
That's a good suggestion. The dog should be evaluated by a Vet, and this can be a problem when money is tight. In fact, more animals are being turned over to shelters these days because people have difficulty caring for their pets in the current economy. Shelters would rather see people keep their pets, so they might be able to help or refer you to a Vet who is willing to make a reasonable financial arrangement. Shelters often have dog trainers as consultants, and these people can also help with behavioral problems, like housebreaking problems.
Using a product to neutralize urine odors is also a good idea. Dogs do mark their territory with urine, and they can return to the same spots. Products like Nature's Miracle, are much better for that purpose than vinegar or disinfectant.
Don't view this situation as your dog simply being defiant. The dog appears to have some real problems, be they medical or behavioral, and both you and the dog need some help in this situation. You need to have the dog evaluated if you want to keep her. Call an animal shelter, or your Vet, and explain the situation with the dog, and your financial problems. See what they suggest.