moving forward...falling back

I've been distracting myself with a new adoptee... a three year old that comes with no info at all. My sister called me and said she was at animal welfare, just dropped off, with an unusual pedigree- siamese and gray tabby mix. She seemed very sweet and lovey-dovey at first, albeit a little skitish. Several days later, she's actually kind of crabby, talks all the time like she's yelling at you. I'm just trying to give her love and space....maybe that's what my mother said...