Need some opinions. (Mental illness etc.)

Hello fellow listeners or members who might be reading this. First off, if this thread is in the wrong section, I apologize. But let's move on to the topic I'd like to decide.

First off, I want to make it clear to anyone that I am not seeking for a diagnosis or for advice. Just mere opinions. So please don't offer me any medical advice and don't try to diagnose me. That's not what I want. I just want to discuss some of the things I'm dealing with, and see if anyone also feels that way and might have an idea what spectrum those things fall under.

So, how do I explain this. Ever since I was a kid, I can remember that sometimes I'd just start feeling really weird in my mind.It would start to feel like I don't exist. It's such a confusing and scary feeling. When it happens, I find myself asking "Wait, am I real? Is this real, do I exist?" I can't quite put it into words. It feels like I'm not in my own body. I guess one could say I lose sense with reality and it all feels much like a simulation. It takes me about a couple minutes to I guess start feeling normal again. I have no idea what this could be, and it's confusing, because it's been a reccuring thing for 21 years now. Any ideas what it might be? I've heard of Dissociative Identity Disorder but have no idea if my experience matches any of the symptoms. The word "dissociating" though hits home a lot. Because I guess in a sense, when I start feeling that way I do in fact dissociate from my surroundings, and even from myself.