well there you go!
Shes probably feeling bothersome and just wants to STAY in one place. She's fixing to have babies so she REALLY needs tyo find a suitable place to give birth. Cats are very picky about those things.
She's been to two new places in a short time, so Im sure she wants assurance she will stay here before giving birth.
If the kittens are coming soon, then she will meow alot. Some do and some dont, but the female pregnant cat I found not 2 long ago was just meowing like crazy. Like stated before, give her some privacy and calmness, right now is deffinately not agood time to get aquainted with any other cats.