At your level you should try focusing on one thing at a time instead of trying to do finished portraits. I reccomend you to start with head construction itself with focus on 3d form of the head and it's center lines. Besides the proportions being wrong, your center is way off from your reference. Like for the black woman notice how her nose completely overlaps her eyes because she is looking sideways, but in your drawing both her eyes are visible. Also try to note if the head is tilted upwards or downwards or if the eyeline is at an angle. So for now I recommend you to practice getting the center lines right.