I'm sorry to hear that you haven't gotten much help. I did find this research type of article that provides more information and might offer some insight that helps.

-- Management of nightmares in patients with posttraumatic stress disorder: current perspectives: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6263296/

The Veterans Administration also has some information that may be helpful --- PTSD nightmares: Is there an effective treatment?: https://www.research.va.gov/currents/0319-PTSD-nightmares.cfm

If you don't mind sharing, is your PTSD related to trauma of some sort?

Hi, I have PTSD nightmares too and use 1 mg of Prazosin before going to bed. Prazosin is also called minipress. But it’s important that if I wake up in the night, I have to take another dose before going back to sleep. Otherwise I will have nightmares in the morning. Another issue I found is that if watch movies etc that have morbid or frightening themes right before bedtime, I will often have nightmares from those too. I found an interesting article that you might be interested in. It’s at this link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3896131/
It’s titled High dose Prazosin for the treatment of post traumatic stress disorder. New evidence is showing that doses as high as 16 mg are now being prescribed and there are no significant issues with side effects. I hope this helps. These nightmares are so terribly terrifying and impact my life significantly too.