I adopted 2 cats from an animal shelter. they were 3 and 1/2 months old. they were scared to death when I first brought them home. they ran from me, hid all the time, and hissed when I got near. I put them in a bathroom with their food, water and litter and kept them contained there during the day while I was at work (the house was overwhelming to them). at night I brought them out into my bedroom (were they would promptly hide under a dresser) and would try to engage them in play with feather teasers. eventually they came out a little at a time and would play. after 2 months they let me pet them and started to approach me. one of them loves treats, the other doesn't so I entice the that does with pounce all the time. it will be 1 month for me on sunday that they have been out of the bathroom. while they still run when approached directly they now jump on the bed with me, rub my ankles if they approach me and are much more social. it takes time, but if you are determind, you CAN bring the kitty around.
It doesn't sound like your kitty is as antisocial as mine were, mine were feral & not used to people at ALL. give her time and she will come around. let her get accustom to her new environment, and if she's not comfortable with you petting her, engage her in play. it will relax her. even if it takes a couple days for her to even want to play, she will come around. she is just scared.