My niece once thought her cat had disappeared. She was distraught, searched the neighborhood, etc.
The cat had crawled into the bottom of a chair, above the bottom lining but below the springs, and was using it like a hammock.
Check chairs, the bottom of your bed, behind the stove, the space between the refrigerator and the wall, etc.
I'm betting that she's in the nasty recliner couch that needs to be put on the curb. But I don't know. I've checked under the stove, behind the fridge, everywhere. She's just got super stealth. She'll show up about 1900 to get food. Her working hours seem to be from 1900 to 0700 the next morning. ;>)
/john