Female Casting

As none of the girls I contacted would like to be a part of the work I'm struggling to find the right girl. I'm very specific on what i would like her to be like so it's becoming increasingly difficult to cast someone as Jules and may have to play her myself, or ask my younger cousin. The only problem with asking her is that she is only 15 and may not look right for the part. As this develops I will write a post explaining my conclusion.