You are doing really well IMO if these are your first gesture drawings. While the figure proportions seem to be really good and you definitely have drawing skills, there is little happening within the "contours" so let's work on that. Don't focus quite so much on the edges. There should be (and usually is) a lot going on within the figure, even under the skin, such as rib cages, bone protrusions, muscles, fat rolls, etc etc! My suggestion is, for the first portion of your timed drawing, don't even touch the paper. If it is a 30 second drawing, maybe look at the figure for 10 seconds and make decisions on how to capture the movement within. Start "inside" the figure even. Hold the pencil loosely and make ghost motions over your paper to feel your way around it. For a 5 or 10 minute drawing, maybe focus for 30 seconds before drawing, and really "SEE". Gesture drawing is all about learning to see. That first thirty seconds will seem like an eternity, but will be the most beneficial part of your time spent. See the angles, negative shapes, spacial relationships, movement, etc, then capture it!