You have done a sterling job to change your dog's view of life in such a short space of time. She is no longer in a total panic about you every time you leave her sight - just imagine what a difference to her life that must make.
One accident.....paaah! So what? (try washing the spot with biological washing powder that you would use in your clothes washer)
Your dog is not BAD - just in a bad way.
Can I also say that this has not got a time limit, when you have taken the pressure off your dog it is important that you don't let old habits return.
I'm not sure what you mean by being firmer with her. It is yourself you need to be firmer with, not the dog. You need to be sure that you have no eye contact with the dog when you leave or enter a room and don't speak to her until she has been relaxed and settled for a few minutes. Then she must do something for you before you give her any attention - a simple sit is enough and then you can show her how pleased you are to see her. If she doesn't do as you ask simply move away from her and ignore her for a little longer. You must be totally convincing and totally calm. Ignore her if she asks for your attention until she has been calm and relaxed for a few minutes - then ask her to sit before she gets any fuss. That is all - no shouting, no getting angry and no forcing. It is her choice and if you can do this she will choose to relax quicker each time.