This is going to entail a lot of work, but your best bet is to call each registrar
and have them try to search based on guesswork (i.e. registrant name, email
address used, etc.).
Good luck on getting your names! Another thing is to check your email for any
updates or notices from any registrar with a domain name in it.
Be sure to keep a list, of course. A simple excel list will do.
Good luck!