a glimpse of happiness

Frederick,

 Congratulations on finding such a natural beauty.  I can understand the desire to use natural light, but in this case the model naturally has very dark hair, the wall behind is naturally dark and your picture comes out with her hair blending into the background - unnatural looking.

What to do?  Consider a large reflector on a huge stand, that can be adjusted to reflect some of that natural light onto the hair -OR- consider using an electronic flash unit on a stand, putting most of its light on that hair.  Also it is possible to bring a fabric background of a light color with stands.  Or, it is possible that a brighter setting was nearby and could be used.

Jerry 

I've just posted another version of the same model "in the light"... and living  color... 

Very good appearance of being so relaxed and natural. Her comfort before the lens comes across clearly. Pretty subject as well, with nice light in her eyes