I hope it is fine for me to post here, I have not been officially diagnosed with PTSD/cPTSD, but I have some symptoms, and I just would like to ask some things from people who experience similar things. I apologize in advance for the wall of text, I couldn't really find a way to make it a whole lot shorter.

I had a pretty rough upbringing, but up until very recently, I wasn't struggling with my past too much anymore.

I am going to therapy for a bunch of different things (substance use, anxiety disorder, panic disorder, depression, and a bunch of random things just floating around). About three weeks ago, I started having a new problem. I talked about it in therapy last week, and my therapist said it is "probably flashbacks". So I am wondering about some things concerning flashbacks.

I experience two slightly different things, and I am not sure whether it's both flashbacks, or whether one is more of just intrusive memories or something similar. It doesn't matter that much to me what exactly it is that I am experiencing, but I'd still like to know what other people experience.

The first case is pretty obvious to me, but only happens very rarely. I will be talking to someone, or be doing something. Suddenly, upon hearing a certain term, or seeing something related to it, I will be almost completely back in the past. I can still see the place where I am actually in (for example my room), but at the same time I can see an event from my past. As in, I see an actual image (I assume in my mind, but it is very hard to tell, to me it almost seems like I see it in front of my eyes). I also feel things that I felt back then. This lasts for about 30 seconds, and then I am "back". During that timeframe, I can't tell that I am not in that past memory/that this is not currently happening.
From descriptions I have read online, this is pretty close to what most people call flashbacks.

The other case is a bit more confusing to me, from which I get a bunch of questions surrounding flashbacks. I will also remember things from my past (things which I actually try to avoid thinking about and have pretty much forgotten about in the last few years). I don't decide to think about these things, it just suddenly happens. I can also see those situations in my mind. I feel as though it is happening now or has happened just a bit ago, it hurts me just as much as it has back then. However, I can still recognize that I am not in the past, I see my surroudings and recognize them. But even though I know this is from the past, my emotions are as though I am reacting to a current event.

In the second instance (I am not sure about the first because it has only happened twice), people can come in and start talking to me, and this will somehow break my focus on that memory and I can (kind of) concentrate on what is going on around me. However, my mind will go back to the memory as soon as the distraction from outside is gone (unless it's a longer distraction). Usually in these cases, about 10 minutes of an event are compressed to maybe 40 seconds to a minute of memory.

I realize everyone is different and these questions might be overly general. I would just like to hear from some people what they usually experience.

1) what exactly is a flashback to you? Is it always the case that you cannot really recognize anymore that the thing you're experiencing is in the past?

2) is it possible for people to talk to you while you are experiencing a flashback such that you "snap out of it"?

3) my therapist asked me whether I see things that go with the flashback. I certainly did for the case where I am pretty certain I had a flashback. However, I am a bit confused about this question and wonder about something relating to it:
is there anything special about seeing (or hearing, smelling and so on) things from your past? When thinking about this, I would say that I do not have a lot of visual recollection for most of my memories. If I think of a childhood friend, for example, I can maybe pull up half an image (I for example remember he had blonde hair, and I know from pictures what he looked like), but I don't have an actual instance where I can link an image and a story or other memory. With these recollections, it's a bit different. I can describe the type of light there was, what the weather was, where I was standing, what people looked like... is this in any way different from a normal memory people have about important events? This might sound stupid, but I can't really tell...

4) This is about triggers. For at least the first situation, I can clearly tell what triggered it. However, I wonder what kind of things can be a trigger. Is it only words, smells, sensations and so on. Or can it also be a general situation? For example, if a child was often left alone and was traumatized by that, could it be that it is a trigger to be alone in a room or something similar?