Hospital Failed To Get Dnr & Now My Dad's Dead

My father had a live-in girlfriend. He was diagnosed with cancer Dec 21st, 2023. He went into the hospital on Jan 17th,2024 due to blood clots moving and he couldn't breathe. At the time he went into the hospital, TN had a major weather system that was so bad even the interstate was closed. I relied on my Dad's girlfriend to relay me how bad it was (at the time she told me he was stable and okay). I found out the day he passed that his girlfriend told doctors and nurses she was his wife. Also unknown to me, he underwent surgery to remove the blood clots and crashed. Once the doctors got my Dad back, they were waiting for his stats to get stronger in order to finish the surgery, the doctor and nurse went to update my Dad's girlfriend (thinking she was the wife) and she informed the doctors and nurse that my Dad had a DNR, she had medical POA and to stop working on my Dad. Three times the doctor and nurses tried to inform my Dad's girlfriend that was he back, and they wanted to continue the surgery, he just needed stronger states. But the girlfriend insisted he had a DNR and she had medical POA and to stop all work on my Dad. The doctors obeyed and my Dad lived nearly 19 minutes without medical assistance before he passed.
After I got the call my Dad died (which you can imagine was a huge shock for me), I was finally able to get ahold of the doctor and found out about all of this. The doctor assured me if they were able to continue working on my Dad, the doctor was fully confident he could finish the surgery. It took me months but I got my Dad's medical records and found out about the DNR and medical POA. I immediately called the hospital and it turns out that the hospital has NO DNR nor any type of POA on file for my father. They took the girlfriend word that they were married and had a DNR and medical POA.

MY question......when I call local lawyers to find out how to peruse this with the hospital and my Dad's girlfriend....how do I categorize it? Because I have been calling lawyers (I've spoke with 6 so far) and no one wishes to take this case and I am unsure why. I have been asking about "wrongful death" because that was the closest thing I could find to match my situation. Am I doing this wrong?
What other options do I have at this point?

I don't think the hospital nor my Dad's girlfriend should get away with this but I have no idea what to do. By the way, I looked up TN law on DNR, and in order for it to be legal, "...order must be signed by a physician for his/her patient with whom he/she has a bona fide physician-patient relationship, but only consent of the patient or consent of his agent" also as of 2017, you can sign an "Advance Directive" which combines a Living Will, Medical POA, and a DNR into one form. My Dad did NOT have this, but he and I spoke on his wishes and while he would not wish to be kept alive as a "vegetable" he wanted medical assistance to be kept alive.