Ok I looked into your artwork a bit more (and now understand your situation). About copying I meant observing, it's just that a picture is a flat 2d object so I am used to call it copying since there is no "space"and it's easier to coordinate and take measurements with pencil. Considering the time you have you can still do a drawing that would normally take you let's say 7,8 hours in two days. All I am saying is that you need to play around more a little. Now that I looked at your most recent work I would most certainly recommend you looking more into perspective and shading and don't press that hard with the pencil, try making more delicate lines, normally the lines should be of equal value of the highest value of shading next to it(so if there is a very dark hole, make a dark line).
Check these out (if you haven't already):
http://www.placidchaos.com/Loomis/
Loomis has the best books about anatomy and has some information on shading and perspective.
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