you need to make yourself more interesting to the pup,make her want to be with you from the inside out,
calling her in cases like that dont make a jot of difference,because your voice is not stimulating anything inside her, its got to come from her,
if its a fearful pup, i would practice bite work with a tug toy, if you get her to bite and tug ,you will create a bond based on drive and drive is harmony with its surroundings to a dog,
it will also go a long way to getting the fear out,,
dont tell her off for making contact with you of any sort,
sensitive dogs are more prey like than pr