I'll start with the things I especially liked about the drawing:
First, you captured well the likeness of Edward and Bella - especially the former. Also, the faces are highly realistic. My favourite parts are Bella's nose and mouth and Edward's eye and hair. In the skin, the bright lines add to the realistic feeling - especially in Bella's face.
The higher side of Bella's hair also looks really good, especially thanks to the difference in brightness from the dark background.
Now about what could have been changed a little in my opinion:
The background would have looked better and contrasted with their faces were it darker - maybe even close to black, and smoother.
Bella's hair could have looked more realistic with more light and darkness contrast - parts of lighted locks and darker shadows instead of dark lines that may give a feeling of hair, but look a little less real. Another small part is Bella's jacket which is a little plain. More details of shadow like on Edward's jacket, and blending the pencil strokes could have given it a more realistic look.
About the originality of the picture, it seems that many artists have used this reference photo, which makes it less special from this aspect, but from the technical point of view (which I tend to value much more) this is a very good drawing!