The anatomy looks pretty accurate, but it doesn't read very well as an upper body to me. I think Steve's version fixed that. The drawing is built with clear and characteristic pieces that the viewer recognizes as body and muscles. The part that I have a harder time reading is her right arm. I didn't notice the hand at first so it read more like a wing to me. Clarifying the hand might help with this.

Hey Liandro, I like your idea here of the all powerful mother and how she is like a superhero. I really like the head shape you designed and the simple vs complex design overall. Now, this is only my opinion, and the way I would do it. You have a distinct style, and I wouldn't presume to mess with that. But, I did a little sketch with some notes that show some of the things I would do if this was my drawing. For example: the centerline of the back makes it feel like it is rotated a little. So, I added overlapping lines to show that perspective. Now, this may be a style thing so feel free to ignore it. I hope it helps :)

This is dope! I think simplified it looks great. It's all there, the lats, the traps. The muscles of the right arm could be adjusted a bit. Pop that rear deltoid and maybe add some brachioradialis for the forearm. I'm somewhat of an anatomist by trade (med school and massage school), but I'm nowhere near being able to draw to this level yet so I'm not sure I this input helps or translates.