Some tricks on the eyes. First look at some dog skulls on line photos if possible so you can get a good idea of where and how the eye sockets line up. Then make sure the corners of your eyes line up, i often draw a faint line to the corner of the ear, or just below, where ever you can get a secondary placement to line up with. You have the inner corners ok but the outside corners one is pointing to the corner of the ear, the other is pointing to the side of the head even tho it is a straight on view. When you know where the standard is, it is the minor little differences, as in people one eye slightly above, slightly larger, or such that makes a drawing look exactly like the person, but those differences are very minute.
If you can get a copy of this book, a friend bought mine at Barnes and Noble, Anatomische Zeichenschule Andras Szunyoghy and Gyorgy Feher. Knowing how those muscles lie over the bones will set your eyes in the exact spot. There are such fine little differences in the lines that frame the eye that if they are not just exactly so even being very very close, still looks off. keep at it, your making great progress. I think what your doing is thinking only of the surface, when you really have to think from the skeleton up.
Also doing that exercise of breaking down the face into all planes is so insightful...Do your own by feeling and figuring it out, how many planes make up the forehead and work your way down. I did a cat and my face and my drawings made a major jump.
Also if you are frustrated with what your doing, that's a good thing. It means you can see what needs to be fixed, even if you don't know (YET) how to fix it.
Just remember that symmetry is hard but absolute. I do one side and get it exactly the way I want it, then I come to the other side and do my every living best to make them match.
My favorite quote of all....THe life so short the craft so long to learn....anonymous.
