I think the nose problem might simply be from the technique Marc teaches for them. The outline shape for the noses from the class is probably the most in need of shaping and smoothing of any part.
Try watching the short bit, after he roughs in the nose, where he goes and shades them and softens it up, its sped up so it kind of whips by, but you can see how much work goes into making the shapes work during that part of his process.
What you have is, I believe, just the rough boxy shape, which is great, but it won't look like much of a nose until you do the next part too.
Keep on posting!