Yo, did a quick paint over cause I noticed a couple of tweaks that could help get you un-stuck.
Big shapes first: exaggerate the curve of the spine a bunch more, make sure that line is continued up into the neck and base of the skull. It's always way more curved than you think 
Head proportions: First thing is I notice is width, I look at the distance between the side of the head and the corner of the eye. This should be about 1 'eye' width.
Lastly, the earlobes will line up with the root of the nasal bone but will descend below that line as people age.
Hope that all makes sense and helps get you un-stuck. I can clarify more if needed, probably should re-visit some anatomy and proportion stuff myself
