When i brought Sophie home as a kitten, Rosie(Also a tortie) had just turned 2 years old.
Rosie was a real love bug and i thought really hard before i got Sophie because i didn't want to lose the close bond that i had with her
Even though she had accepted Sophie and started playing with her, Rosie did change with me in the fact that she never came on my knee anymore, or played with me like she used to, which i admit did upset me because thats what i didn't want to happen.
About 8-9 months after Sophie was with us, Rosie jumped on my lap unexpected!, and not only that she started playing with me again
I got my little girl back.
I would get to know your little girl better and vice versa because it certainly sounds like you have one little love bug there!