first critique!!

https://imgur.com/a/K6XTXWZ

I am a teen self-taught artist posting my art for the first time. Any critiques would be greatly appreciated!!

The pose is very fluid and you use organic shapes very well. I especially like how you drew the legs, the foreshortened one looks especially good with the way you drew the muscles splayed out a bit where it is laying on top of the block. 
The shoulders are a bit confusing in my opinion. Have you tried the technique where you draw cubes/ovals where the chest and hips should be? If you use cubes, it can really help map out the angle in which each part is rotated in 3d space. It can help to also add little spheres or points where the shoulders are in relative to the box of the chest. 
This is looking really great though, keep it up!