i am not a pro, but i can see there are missing shadows around the eyes, see where the eyebrow meets the nose the shadow there makes the nose have height where it is lightest and the dark area makes the roundness of the eye ball more obvious. also the shading at the right most point of the eye to show depth there. the only other help i have is to look at how close the lips are to the left side of the face. and the shadowy areas at the outer points of the lips. i also struggle with these things so that is why i noticed. the angle of the lips is very deceiving--the lips are smaller on the left side even though we know they are the same size irl, you can maybe see on yours how the left part of the lips seem to pop toward you? it is because you have more of a straight on proportion. I hope this is helpful, it is very impressive you have done a lot of things right. the nose is excellent. enjoy!