Have you logged into the account since 2011? If so it's mandatory that all YouTube accounts are assigned to a Google account, do you remember the names of your Google accounts? If so you can get access without your email address with
account recovery.
Subscribe to your channel and comment in a video, if you have notifications enabled, you'll get an email notifying of the comment & subscriber.
Does your YouTube channel show it's linked to a Google+ account? If so then go-to that Google+ page manager and check the email there
