Hello : ) I can see on your previous stuff that you've drawn from life, and thats good. But it seems to cause stiffness in drawings when you use your imagination. You are already on the right path really, keep doing gesture drawings on here. If you give yourself a short amount of time to get a pose down you'll use fewer lines to get the gesture, and get more fluid : )
I suggest you do it everyday or at least a few times a week, it doesnt have to be hourlong sessions, you can do the half an hour class if you want. Just try and experiment and see what makes poses feel alive and fluid. Don't focus on how the model actually looks, only what the "energy" of the pose is.
Draw draw everyday, and for you, I think drawing from your imagination to train that part of you up is a good idea, cos from your studies I can see you are good at capturing what is in front of you, the next hard bit is implementing it in your art : ) this guy: https://www.youtube.com/user/Sycra
has tons of videos explaining things : )
hope this helps : D