Scared Pug/Jack Russell Pup?

I have a 7 month old Jug (Pug/Jack Russell) puppy. When we first got her she was scarred of EVERYTHING but we thought it was only because she wasnt used to the house and was away from her mother. A few months later...she is still afraid of EVERYTHING. The only people she will go near is my fiance and myself. She is absolutely petrified of everyone else! Is ther something I can do to help her relax or is this something that the pug or jack russell breed usually do? Any suggestions?