A pretty classic move for someone walking on an unclear path, dont worry anon I did the exact same thing just shapes and eyes(youre doing better than I did at them though).
What I'd say is Read Drawing from the Right Side of the Brain and Keys to Drawing.
Those should clear up some uncertainty but from what I can see I think youre too good to read those books as theyre for complete beginners so maybe tackle pic related.
Crabs will tell you this list is trash for no good reason, however youre free to do what you like.
TLDR; If youre not interested in anything I just said try ploping those good looking eyes on a figure. You may find what youre lacking if you do that.