As one who's had to do research into the series as an editor for a fanfic, I can say you've nailed the Changeling features pretty well. I haven't really seen any anthro versions before, though, so I can't say whether this is definitively what anthro would look like, or if you're setting a new trend. The fangs are a little long compared to most average changelings, but I assume you added that alteration as part of the changes via the power boost mentioned in your description. As I said, very well done.