Willie,
this is a marvellous picture

i like the tones and contrast!
I'm trying to identify myself on your procedure you have written upon, in order to have a clear reference in mind for my next time!
doing this, a question jumped in my mind:
have you tried to capture this scene from the opposite angle? I mean from the left side of the artist? in order to have from left to right the girl, the sketch and the artist
i'm asking you that because, perhaps this could be the position I would choosed...
thanks a lot
nicola