There's a couple of things that might be helpful to remember here. First, everyone has different personas - if my doc started talking to me the same way he talks to his wife, I'd be worried. But just because his personality changes from "Work-Doc" to "Husband-Doc", doesn't mean he's got DID.
Memory is a tricky little bugger - there are lots of reasons that our brain doesn't allow us to have conscious recall of memories. For me, yes, it's probly the DID thing. But my sister, also mentally ill but no form of dissociative disorders at all, doesn't remember her life till about her late 20s.
Third, there are lots of different types of dissociation and dissociative disorders. It's a spectrum that everyone sits on somewhere - for a healthy person, it might be driving home from work and not remembering any of the trip. That's dissociation in a healthy form. DID is only one of the different types off dissociative experiences. Other types, such as derealization, are recognized as a disorder and have similarities to DID. It's quite difficult to diagnose unless the person either has good insight into their own symptomatic history, or the clinician knows you well.
Don't freak at the label, it is a manageable condition. Read what you can - from specialists and sufferers alike - because, IMHO, that really helps to understand, accept, and deal with having the condition, as donmany of the threads under the Flashbacks & Dissociation header:)