Your shading is amazing, followed by your techniques and how you sketched it. but, you always make the same mistakes, your eyes are somehow uneven, and the way you place the eyes, mouth nose etc... is kind of... well, strange. the rest are fine, this sketch is quite fantastic excellent job!
I also have the same problems, like everybody hes, including you, we all cant draw the exact shape, size etc... but we try to make it look same.
always, the first sketch we draw is better than the second. because the second one looses its originality; the first eye is perfect, but the second is not, why?
We can't copy the exact same thing, thats what we, human cant do. that's why we need to try our best to keep it the same.
hope this will make you improve!!