gesture

I think your anatomy looks pretty good! You could work more on the hands though.

This a very, very good figure. The proportions look just fine. Is the right leg bent forward at the knee? Your study of anatomy would tell you that the upper leg ( hip to knee) and the lower leg ( knee to ankle ) are the same lengths. The upper left leg is seen in foreshortening and is drawn correctly.

You want to draw from your imagination. There is nothing wrong with that. Keep up your study of anatomy - muscle & bone structure. Make drawings of these so you can imprint these on your mind.

You might think this is funny but to get things in the correct position & correct relationship, draw the figure using stick figures. Start with the head & shoulders. Same thing with the hands. For the feet thing triangles in any view. After you get all this worked out you can progress to fill out your figure.

In anything, practice makes better. So practice, practice, and then practice more.