Nice story so far. It seems to be more about Tonks than Harry so far. He's not much of a character in the story.
You mention Dumble using the order for security. There is no order in canon at this point in the time line. The order is "reformed" after Voldie is given a new body. But before book 5, there is no actual Order of the Phoenix.
Author's response
As to the Order: I was going to add a "former" in there for clarity, but I just watched a panel at an SF con where the consensus was that it was inactive, and not disbanded. So I think I want to stay out of that particular question, since I don't want people thinking "former" means they quit. There is also the question of Dumbledore's perceptions vs everyone else's -- he might very much be in a wartime mindset when no one else is (that also seemed to be the consensus at the panel). Personally, and for the purposes of the story, I just haven't made any decisions about those nuances yet.
As to Tonks vs Harry -- yes, that's correct. This is not intended to be a Harry-centric story, at least in terms of whose perspective it is told from.