Yes, I agree with Aly and check the house again. I know you've probably done this a hundred times but cats are so sneaky.....

My Siamese once got into a partially open drawer and someone came along a closed it on her....it was not a room we used a lot so it took us a while to find her. Then another time (actually it's kind of funny now) someone came in to my apartment to work on the water pipes. To do this they had to move the refrig and take out a panel in the wall. Well when he left to get something, my curious cat and her sister went in there and when he came back they were too afraid to come back out so, yup, you guessed, it they was walled up. Not only were they walled up but I was on the third floor and there was no flooring in that area so she was sitting on a beam in the dark. Fortunately I came home early that day and when they didn't greet me I tore the apartment apart. Then I went over to the office and they sent the repairman back but he insisted he never saw the cats and that they wouldn't be in there... I made him open the panel anyways and thank God I did because out they strolled like they'd spent the day in the park. He was flabbergasted and I think I was in shock. I never heard them make a sound when I was calling for them........
So I'm hoping for you that she is hiding someplace and just being a cat... I'll keep you in my thoughts and prayers.