Mia sounds like what I call a "cat's cat".
That's actually what I came to say.
I've seen quite a few, even some that were raised from babies, that only really came to people as a food source and preferred the company of cats.
And as far as the nursing not odd at all, especially if the kitten was fully weaned by 6 weeks, which is a bit young. I've had cats that would try to nurse on my hair or ears to the point of drooling everywhere. I've seen it more often with kittens that were weaned a bit too young, but also with cats that were raised and weaned normally. I think it gives them a sense of euphoria just like it would a baby that is nursing. You notice you will see baby kittens happily suckling on a moms belly or other areas when they're not even hungry or getting any milk and falling asleep while doing it. It makes them feel good and it comforts them. You also see it with other animals that nurse, including humans. I think you could probably relate it to a child that sucks on a pacifier when they're passed nursing age, or sucks their thumb or other objects like a special blanket.