As mentioned, leaving yourself some room for cropping afterwards is always helpful. Taking off the top of the head can be used in an extreme close-up, but it doesn't work in a mid-range shot that includes the knees.
I think I understand what you were going for with the space to the left. This works better with a more neutral background:
Since the fireplace provides such a strong line, it is a little more important with that setting that it is either deliberately straight or deliberately slanted. Having it slightly off makes the picture feel slightly off. In the picture above it is more clear that the bricks are not straight on. Another option might have been to have them a little more away from the fire place and use a shallower depth of field to throw the fireplace softly out-of-focus.
All of the suggestions aside, you did a nice job exposing the skin tones!