Before you do anything else, try this simple trick: open the image in an image editor and flip your drawing horizontally. It should immediately become apparent to you that the drawing has various issues:

- the diagonal lines in the background are a BAD thing to have while drawing: your brain will attempt to compensate or align edges, and that just causes issues right from the start. Either draw on blank paper, or math paper with straight 90 degrees lines.

- the face is more or less positioned horizontally, but the line that runs through the eyes and nose is diagonally running down to the right.
- while the face shape is drawn from a mostly frontal viewpoint, the eyes are drawn as if the head is turned.
- eye shapes are incorrect. Eyes are generally not drawn as triangular shapes. Round, ellipses in cartoons. A realistic eye looks nothing like these, of course. But triangles... No. Unless you mean to draw in an extremely stylized abstracted style, of course.
- the mouth is positioned in the wrong place.
- the shoulders do not match.
- the finger/ hand is incorrectly drawn.
- the arms and shoulders form one flat shape.
- the pupils are skewed. Pupils are always round in humans, and round when viewed in a frontal view. Used in perspective/turned head this rule changes, obviously. In that case cartoony eyes are drawn as an ellipse in perspective.
- the crosshatching (lines) are too wide apart and inconsistent.
- the placing of the shadows is incorrect.
- the placement of the eyes and nose is incorrect.
- the neck attachment is odd.
- the overall figure's proportions are incorrect.
- the hair is incorrectly drawn.

But in truth, all the issues apparent in your drawing (and the others you posted) share the same underlying deficit: a severe CRIPPLING lack of knowledge about proper CONSTRUCTION of shapes.

It's as simple as that. :-)

When people suggest that you learn more about anatomy, what they actually mean is for you is to learn about properly constructing the foundational forms and shapes of a 3d human and translating those to a 2d drawing. When others tell you "your drawings lack (or have the wrong) perspective or 3D", what is really being said is again: you lack understanding about how 3d shapes are CONSTRUCTED and how those translate to flat paper.

Same with shadows and lighting: you have no hope in heck to understand how these are applied in a drawing unless you understand how basic shapes are constructed in 2d.

What is more, after you understand the underlying construction (foundation) used in a drawing, you can adapt to that style (relatively) effortlessly after some practice, and draw within that style.

YOU MUST LEARN PROPER CONSTRUCTION to improve your drawing skills. If not, your drawings will always look "wrong", even if the quality of your lines may have improved. Trying to copy a certain style without understanding the construction principles used by the original artist(s) is an endeavour that only ends in frustration and, at most, mediocre, results.

Anatomy, for course, is merely learning about the shapes of the human body. You must learn those (at least the major parts), so pick up a good book on anatomy for artists.

To learn more about drawing (cartoon) characters with proper construction, I refer students to JohnK's animation drawing "curriculum":
http://johnkcurriculum.blogspot.ca/

The first lesson is about constructing 3d shapes on flat paper.
http://johnkstuff.blogspot.ca/2006/05/animation-school-lesson-1-construction.html

Good video library for the beginning (digital) artist:
https://www.ctrlpaint.com/library/

Other books:
- Terry Moore's How to Draw
- Eric Goldberg's character animation
- Richard Williams' book, of course.
- James Gurney's books (get the one on Color and Light).
- Juliette Aristides Lessons in Classical Drawing
- Betty Edwards The New Drawing on the Right Side of the Brain (to learn to 'see')

Generally avoid tutorials and books that only teach quick 'recipes' to emulate a specific style. There is no need for those, once you understand construction in 2d drawings, whether they be in a realistic style or an abstract visual (cartoon/comic/manga) style. Books by Christopher Hart are to be avoided, in my opinion. At least, perhaps at the very end of your learning process might you have a look at them, and then you will understand that those books are junk anyway, and you will not need them ;-)