I posted a similar version to the coord that I wore today on a post on daily-lolita a few weeks back so that I could get some feedback on it. The main criticisms I encountered were comments on the dress being too short and issues with my hair being too plain.
I looked into investing in an underskirt first. However, I started imagining what the dress would actually look like with an underskirt, and I just didn't like the look. I do think that the dress will slacken and lengthen somewhat once I lose some weight. So for now, I think I'll keep rocking it at this length while making sure to wear tights so that my legs aren't exposed at least.
The hair thing seemed easier to solve. I decide to start wearing my hair in fluffy pigtails on either side. I wish the flash hadn't keep blurring the picture for some reason so that the hair would be better illuminated. I overall like the look of pigtails a lot better since I was getting tired of keeping it back in a bun anyway.
Also, though no one commented on it, I decided that I like the look of white tights better with this outfit. They seem to bring out the white of the blouse along with the white in the dress more, and the I think the coordinate has a nice balance as long as I keep wearing black shoes with it.