Thanks cstew,
This is looking good, only a couple of notes.
I think you've used basalt cobble for the roof tiles, whereas the White Harbor roofs are generally bedrock/basalt brick/or black slate. Most house roofs add a block of northern wood stairs along the edge too.
Would be good if you added half doors to the rafters as well to show a little more structural support.
The upstairs level is looking a little cramped for space, which I'm guessing was what stopped you from adding the wooden stair/half door roof rafters.
It's not always possible but it's good to try and plan the upper layout to give you one more block of height on that upper level so you've got the space to add the rafters. Here's some examples
For your next challenge, please build a middle class house in the style of /warp hgtown. Like this White Harbor house, a house in Highgarden will usually have a profession on their on the ground floor, take a look at the finished houses in the Highgarden town area for inspiration, and give the house some kind of profession that would make sense in Highgarden/the Reach (e.g. potter/candle maker/carpenter/wine merchant/blacksmith etc).
Also have a go at uploading all your screenshots to an imgur.com album, makes it a little easier to read them all in one place rather than split out with each in their own post.
Good luck!