AA and Freedom Frog... I am very glad Kitty did decide to come back to visit (at least for a while). You aren't going crazy or schizophrenic, it is natural. You (as many others have found) will probably experience these things for a while before Kitty makes her way over, though sometimes pets stay around for good. When you hear her meow, let her hear your voice, and tell her you love her and miss her.
Keep an eye on her favorite places and or toys too... you may even notice things in different places when you leave the room and come back in, she's just as playful as ever! Open your mind and your heart to her, and you will probably notice these things a lot more.