I feel that way a lot. Sometimes I just don't feel like me and don't know who I am. I thought that meant that I don't have DID, because I thought DID was all about complete alters being totally separate but my therapist tells me that experience of not feeling like self is really common in DID too. Sometimes the dissociation and splits are complete and sometimes they are "fuzzy".
I really hate it when I feel "not me" but it isn't a switch with another part being them it is just me feeling completely different.
Ultimately I suppose all of the parts have to be felt as part of the self so I guess there are lots of shades between "black and white".
I am very tired and I think I am just rambling. Sorry if this wasn't what you meant at all!