No one here can really diagnosis the condition or the symptoms online. Working with the professionals is the best way to sort it out, as hard as it is to keep asking them. It does sound like you are getting triggered and managing being triggered makes it very tough to focus on anything else!
Flashbacks tend to be very intense re-living experiences. When I have a flashback, I don't realize it until after it is over. Like I will be walking down the street and suddenly cowering like someone is hitting me and thinking the past is happening again now in that moment.
Intrusive memories can be very intense to experience too. It's my understanding those are more like when I'm walking down the street, and I know I am walking down the street and I know no trauma is happening now, but I feel the feelings and memories from the past are stirred up and I'm thinking/feeling it again. It can be a physical memory or body sensation, or emotional one, or it can be a memory of something that happened in the past that is playing in my mind that I can't easily stop.
There can be a big overlap between what suffers and professionals call flashbacks and what they call intrusive memories. This is just my understanding of the difference between those two. I would not say one symptom is more "serious" than another. Intrusive memories can be very awful and disrupting to experience.
When people have nightmares without PTSD it can be very hard to wake them out of the nightmare and they can act out the nightmare a bit. It could also be the case that nightmares turn into a flashback for someone with PTSD.
I think the best thing to do is to describe your experiences as they are. Rather than say, I'm having flashbacks, or whatever label, tell them what you experience and are struggling with. That will give the most information to the therapist and doctors for them to be able to help you the most. In time, you will be able to sort out what is what symptom for you, and most importantly, get better!