There is only one way to know who you registered your e-mail with and that is to look in your mailbox and see who your getting e-mail from. If you suspect that you registered with a specific email somewhere but not sure you can always go to that website and click on I forgot my password and/or username and have the site send you an e-mail to reset password. If you see a email from them then you did, if you don't see an e-mail from them then you didn't.
There is no central reporting of who has what for registered e-mail addresses. Additionally there is no trail on gmail for any sites you registered with unless you had to respond to the website to confirm that your a real person by responding after registering in order to activate the account that you created.
