Argh. Postage failure! 3X! I can't re write the whole thing now.

I'll hit the major points quickly.

Everything you mention experiencing, I have experienced. And more. There are few symptoms I've seen listed that I haven't had. Including eye color changes, if every GF I have ever had can be believed.
I was also told the same things. Vivid imagination. Over active imagination. All in my head. Making it all up to get attention. (I actually avoid attention)
If you re going to talk to a psych, or a therapist, definitely bring up how far back your symptoms go. They should ask about that, because DID is formed fairly early in life, for the most part. Some say differently under some circumstances, others say early childhood, or not at all.
Printing out your post can make bringing up the subject and the symptoms easier. Or just to keep you from leaving anything out. It can be Hard to talk about.

From my own experience, I thought that a diagnosis would prove I actually really had DID, or prove I did not. And if I did, I would be finished with all the denial. It helped. Mostly with telling those I felt needed to know. But not as much as I wanted for myself. I'd still like to wiggle out of it.
What really matters is how you feel. What you believe.

I believe if you think you have DID, but worry that you might be wrong, you probably do have it. Because you'll be careful about matching your experiences up with the symptoms. And if you are fakeing it, or making it up, you aren't going to worry about if you are faking or not. Only if people believe you. But that's just my opinion

Jax