Since the purpose of the bean is to help simplify the twisting of the torso, if you're better able to visualize that with a flour bag instead, then you can replace the bean. The bean is meant to be used as an analogy, but you should use the analogy that best suits you. If you're more comfortable with a flour bag, then use that instead.

You're sticking to close to the basic structure of a human rather than trying to find the motion of the pose. You can understand how the person is posed through your sketches but you don't need to define the rigid structures like the torso and pelvis like the ovals you've been using. Try to use long lines. Since they are your first sketches it should be fixed through repetition.