A nice Harry/Hermione story as always. I enjoy their interaction. I also liked Hermione's mother and her mildly catty statements about other mothers.
Additionally, your Luna is, from what little we saw of her, a more normal version of what we usually see from fanon and its a little refreshing to see her as such.
You have labeled the story as complete and to be honest it does stand on its own, but like Family Surprises, it could also be expanded if you want to take the time to write more. An addition could be about the whole year, or just a one shot about when they tell the Grangers about being already married (though I would probably vote for the longer version).
Minor correction:
I think you meant nine month anniversary instead of "ninth anniversary." Otherwise, the daughter would be way two young to be in Hogwarts with Harry and Hermione.
Finally, I look forward to seeing the next installment of Motorcycle.