Not everyone's system is structured that way, and that's okay. Not having a host isn't that unusual, really, based on what I've heard from other people with DID. We tend to go through phases with who's out front the most--it'll be one of us for a while, and then something will shift and another group will take over, or a different primary host. So in that sense we don't really have a single host either.

Basically, there's no wrong way to be DID. Everyone's experience is different.