You have a good mastery of drawing with the pencil. It is a tool you know well. However, I see repeating errors in your drawing of faces and heads.
You are struggling with the facial feature forms. For instance, even when your subject is turned 3/4 view, you still want to draw your features like if they were straight front view.
You drawing of eyes are very iconic and you seem to spend a lot of time on them but they are not right. If you look carefully, you will see that they are not like they appear on the photo. You need to try avoid the eyes like you used to draw them and try drawing then like they truely are in the reference photos. One very good trick to avoid drawing the iconic representation of facial features from photo is to turn the photo reference upside down and draw upside down. Then draw the same photo rightside up and compare the two drawings to see what I mean. You have the same issues with the mouth and to a little less extent with the nose.
If you want to improve, I would recommend that you avoid reproducing photos for a while and start studying head anatomy. How head features are build (their form, morphology). Start drawing from life too. Just draw heads from all angles and use anatomy book references.