Not sure what to do now.

[Yeol]

Sony can give you the PSN ID but not the e-mail address used to create it. You have to provide all possible e-mails that you might have used to create an account and they will check if it exists in their system or not.
I suggest providing Sony with as many information as you can to prove that you're the owner of that account, information such as your date of birth and the answer to your security question.