OP, if you can stand it, sleep on the couch tonight and see if she creeps out to check you out while the lights are out and the room is still. There is a great book called cat vs cat by Pam Johnson.
Here is the synopsis from Amazon. It might help.
Book Description
In this companion to her successful introduction to cat behavior Think Like a Cat, Pam Johnson-Bennett, the award-winning author and feline behaviorist, shows how adding another cat to your home does not have to be the start of a kitty apocalypse. Although cats are often misunderstood as natural loners, Johnson-Bennett shows how to plan, set up, and maintain a home environment that will help multiple cats—and their owners—live in peace. Cat vs. Cat will help readers understand the importance of territory, the specialized communication cats use to establish relationships and hierarchies, and how to interpret the so-called “bad behavior†that leads so many owners to needless frustration. Offering a wealth of information on how to diffuse tension, prevent squabbles and ambushes, blend two families, or help the elder kitty in your family, Cat vs. Cat is a welcome resource for both seasoned and prospective guardians of cat families large and small.
About the Author
Pam Johnson-Bennett, author of five other award-winning books on cat behavior, is resident cat expert on iVillage.com and the behavior columnist for the Internet magazine The Daily Cat. She has written numerous articles for national magazines and frequently appears on national TV and radio, as well as veterinary and animal welfare conferences. She lives near Nashville, Tennessee.