Nice collection of studies already! There's not much more to say other than what's already been said. You seem to have a good grasp basics of anatomy drawing techniques. You should try experimenting with varying your line weights (thickness). I noticed you have done so with some of your work. The key to realistic anatomy studies would be a keen eye for details. Your gestures are good keep working on those. You will eventually be able to pop these out with no thought whatsoever Also remember, there is no such thing as no tone when it comes to anatomy studies. Even if a part looks blown out or "white" it still has a bit of tone to it. Just get a good crosshatching gradient going and build up the tones slowly, don't rush it. That was one of my main problems! A good use of tone will yield a good sense of depth and dimensionality to your work. It's something I've been struggling with for years... Don't let that scare you, I'm a really slow learner
Atleast you have access to a live model once a week. I've got access to none. All my stuff are referenced from photos which is not the best way but a good second choice!
Take care, and keep posting!