space-sprayer,
Lol, I don’t know why people think that they should be able to draw figures from the imagination right off the bat. Count how many drawings from life + master drawings you have done in your life. It is probably less than 100, maybe even 50. To really build up a good, solid vocabulary of figurative ‘terms’ and memory, you really have to do hundreds of drawings. This can be anything from sketches to full fledged drawings, but the point is that you must do a lot of them in order to eventually be able to draw from imagination. 
You’re at a good starting point. Aim to do a set number of master drawings, say, 20 in a week or 2. Keep setting goals, and doing more drawings.
See this useful thread with links to Master Copy Resources:
Looking forward to seeing your progress! 
Cheers,
~Rebeccak







