You might try getting the flash off camera. The light is a little flat. Adding light direction will help bring out the terrific form of your lovely model.
I like lines in the background but they can sometimes distract when they contrast greatly, pulling attention from the model instead of drawing attention to the model. The light brick and dark lines are creating the high contrast areas. The viewers eyes are often pulled by areas of high contrast, so you want to make sure those are areas you want the viewer to look at. With less contrast I think they would make pleasing leading lines.
Love her hair but it might be hiding a bit of her shape. The black shirt also seems to be hiding the shape as well.
Classic portrait placement of the models eyes in relation to the frame. Great subject!