Interesting process. I think the main problem is the vectoring step (4).
The outer shape's nice (though I find it a little bit odd you chose the shape with very small 'holes' in, as these completely disapear when shrunk down to size, tho could be fixed after) but the shading, is really very bland and predictable and there's only one accent colour. If there were thrusters or something you could use it as secondary lightsource for some nice edge lighting etc. Also it's quite dark, without edge lighting, the outer edge is quite hard to discern on a black background.
Another problem I have, is I don't really understand if the yellow parts are lights, windows, or markings. Lights should glow, windows could have detail and/or glow a little and markings should share the shade (dark/lightness) with whatever it's marking.
Hope this helps!
Many thanks
Rik