Beautiful blue eyes. Nice the way you covered part of the face with a book for added viewer interest. Selection of a Harry Potter book is cute.
Lighting generally OK but not exceptional. Color and overall exposure looks good. I suspect there are several technical features that negatively affected voters. Though the eyes themselves are very beautiful and immediately draw attention, the undereye area is harsh and viewers will vote you lower because of it. And that is partly because the eyes attract so much attention already.
Ironically, it also appears that noise reduction may have been overused to make the areas above the eye browse and on the nose and bridge of the nose oversmoothed because of it.
Obviously, this meets the challenge.
This image is quite similar to another friend's entry in the same challenge that scored much higher. For that reason I suspect that technical quality figured prominently in your score.
Use the blur tool to soften and or eliminate the harsh undereye areas, even to the point of being unrealistic to your model, but realistic to viewers. That will make more difference than anything else.
Review post processing to insure that there is not the appearance of oversmoothing on your model's face.
Sharpening may be very slightly overdone so you may want to back off on it a bit. That is a lesson I've never quite learned myself. :)
Lastly, you have a basically blank background. Nothing wrong with that, but you might consider adding vignetting around the subject for added viewer interest.