It's lovely to see your work, and I like the colours of the latest image very much. I also really enjoy the clouds and background in the latest, which work well for me and offer a sense of the figure as something beyond a portrait.
I'm not sure how much formative critique you are after. I'm a collage artist so although I studied drawing many years ago it's not my area of expertise by a long way. However, looking at other work you've posted here I'd suggest that perhaps texture was something to work on.
I really enjoy (despite drawing not being my strong point) contemporary drawing-games/styles like the 'draw the image with your eyes closed' or 'draw a portrait using only one line/not taking the medium from the paper'. They can be fun ways to loosen up and expand/explore the way you draw, but probably more as sketchbook work than finished pieces.
Anyway, it's lovely to see the process as well as the finished piece, thank you for sharing your work, and the background and head and shoulders of the latest one works nicely, I think.