Having a nightmare every now and then is part and parcel of the human experience. However, what you're describing goes beyond what's normal. These nightmares seem to have become a regularity, and they're vivid. You may feel okay after waking up and realizing the world isn't what you were dreaming, but while you were asleep, you genuinely thought it was real. And that's all that matters.
We typically remember only one dream per sleep, though we have several dreaming episodes a night, in total taking up a quarter of our time sleeping. Maybe you and I are having more nightmares than we want to, though thankfully we aren't remembering them all.
The issue remains: you have these nightmares, and they're having a substantial impact on your wellbeing. I'm interested in when these nightmares began increasing in count and intensity before they disappeared for roughly a year. You said they involved a traumatic event, or an acquaintance. Do you still wrestle with thoughts of this person or traumatic event in your everyday life? Do you dread going to sleep, worrying that you may have nightmares about these things?
I occasionally have unpleasant dreams featuring a couple of people who I've cut contact with for my mental health. Yes, these dreams are really undesirable. I remember feeling how it sucked to be in one nightmare where I was dragging myself on the floor for that person. But when I woke up, I was relieved that she was out of my life. Still, I would rather not have these dreams in the first place.
It seems like your nightmares are a lot more intense. My dreams aren't vivid, but I did take Effexor a few months ago, and I had vivid dreams where I saw a building collapsing towards me. Do you happen to take any medications that might increase the vividness of your dreams? Antidepressants like SSRIs and SNRIs can cause REM rebound, making for more intense REM cycles.
There are medications, such as antipsychotics, that can do wonders in preventing or mitigating vivid nightmares. One of them is the one you reluctantly take: trazodone. But it isn't the only antipsychotic. Trazodone is typically prescribed as a sedative for patients who suffer from insomnia associated with antidepressants. Have you taken other antipsychotics, especially atypical antipsychotics?
The thing with atypical antipsychotics is that they work on the 5-HT2A serotonin receptor. This is the same receptor that is leveraged by psychedelics such as LSD and psilocybin to create hallucinations and out-of-body experiences. (This is why atypical antipsychotics, such as quetiapine, olanzapine, even trazodone are famous trip killers that can take people suffering from bad trips out of their misery.)