In the trial dialog, is there an "Activate Software" button? If you click that, does it ask for your serial #? Or ask you to sign in? If Sign In, what email address is listed?
When you install and activate your CS6 product, it registers your serial with your Adobe ID.
I don't see a registered product under you account using the email address you've used to log into this site. Is it possible you registered under a different email address. Short of that, you'd need to find your serial wherever you misplaced it.