Just a friendly tip, SZ.
See those vertices along the edges? Try to align them in
smooth curves,
like this, from all perspectives -- front, side and top -- horizontally and vertically.
The reason behind this is that, following these principles, you're likely to get a smoother, better and more accurate representation of the reference image.
If it helps, always try drawing the edges on paper with a pen, so you can figure out where to apply it digitally.