Hi Anna,
I have nightmares but have no trauma. I work with kids who have experienced varying degrees of trauma and I'm wondering if the fact that I allowed myself to become too emotionally involved with them has caused the nightmares.
I tried looking for scholarly articles about nightmares without trauma but I wasn't sure what key words to type in. Maybe you could try the same for PTSD?
You said a professional told you... does that mean you're in therapy? My physician made an unsuccessful attempt to stop my nightmares. Now I have a consult for a sleep study coming up, but I'm considering finding someone to talk to, also.
Good luck!