Cats can take quite a while to adjust to a new environment, so that's perfectly normal.Glad to hear that she seems to be settling in. And I love that you adopted a black cat. I've been told by various rescue peeps that black kitties are more difficult to adopt.
We have 3 black ones in our cat crew, one who used to look a lot like yours but has managed to double his weight in the 8 years we've had him, so now he's a giant beast. 😂