I'm not sure exactly how to start this so I'm just going to detail this straightforward. Please keep in mind I had these symptoms before I found out what OSDD was. I've had them since about 14 but I believe I had lesser symptoms before this age, but I cannot remember. My childhood was abusive and I would rather not go back to it.
Anyway, here is the gist of it. I feel like I am two different people. I have my main self, which is me and how I normally act. However I also have times where I feel like I am actually a different person. I do not feel like this person is a version of myself, I feel like she is literally a different person entirely. She has a different appearance that I visualize in my mind's eye. She is around the same age as me though. She goes by a different name, and has a completely different appearance to how I see "myself". I do not see her as me, or as an imaginary figure, however I can almost never talk to her unless it is very quiet inside my mind and then not for very long. The only time I see her as "me" is when I feel like she is around somewhere, that is the only way I can explain it. I get this feeling in my head, like a spacey feeling, I feel compelled to act like she does, her traits are very consistent. She likes to dress a certain way, has her own preferences or whatever, however she does not control my body, she is just a part of me. I apologize for the scattered nature of this post. Questions are fine and greatly encouraged, I want to know what is going on. To add, I have never experienced psychotic symptoms.