How many photo references are you using?  I typically accumulate several photos from all angles, if available.  Photographic images tend to vary dramatically depending on the lense used, angle and subject position.  Such a variety will confirm or dispel specific facial features.  Also, be aware of the subject's mannerism and emotional inflections as they relate to facial morphology.  Very important if you want to give her a bit of genuine life to her expressions rather than a deadpan look.