You should look into draw a box. Perspective and general drawing skills have a really really good ROI. Def some of the best things to start out doing. anatomy is really complex and hard to understand, the way u get better at it is doing it little by little and recognizing how each muscle plays a role in the body.
Dont get discouraged! You are working super hard and making amazing progress, its just hard to see it from your point of view. The balance between effort and progress is something that ALL artists struggle with. Keep learning your what works best for you and adjusting your workflow. Im rooting for you!