I have a female who's a little over a year old and we've been trying to make her social since she was born. She's finally letting people pet her but I'm not sure why she doesnt like anyone at all.
You really can't predict for sure how a cat's personality will turn out once it grows out of kittenhood.
I am not a breeder but I have rescued sets of orphans and even though I have treated them all equally in terms of socializing them, they always grow up to be individuals with different attitudes towards people. I just adapt to their "personality". If one is more timid than the rest, I take more time to let it adjust. Maybe you should do the same. Don't force the issue or don't be disappointed that your girl is not as friendly as you expected.