I can completely relate to you, in every post that you've written so far. In fact, my mind takes it even further and I have thoughts in the third person (please forgive me as this sounds NUTS) as if I have an imaginary friend. I guess this is because ever since I took my first psychopathology course in undergrad, my mind latched onto the "positive" symptoms including hallucinations--- and so I have thoughts in my head like a "voice" even though I know it is my own mind making everything up. AND, I've been seeing a professional who specializes in treatment of OCD and I obtain consistent reassurance that although I am not crazy now, there's no telling where the future may be. ;) He works in CBT treatment, so he does not give in to my checking.
Also I've had the optical illusions scare as well as checking every little noise around the house to make sure it was an actual noise and not just hearing things. Of course, people experiencing the height of anxiety may have extra-sensitive sensory experiences and so every tiny peep or pin drop may sound like a noise or what not.
The best thing to do (believe it or not) is to tell yourself you never know, that maybe you'll be crazy in the next minute-- and you should enjoy your last moments of sanity. This will initially increase the anxiety, then you will find you feel better as you have stopped looking for reassurance.
I hope this helps. And if you have any questions or want any info I am happy to share my experience.