Almost 20 years ago, I’ve got a steam account already. Somehow, I’ve lost the account-name, but I still see it in the friend list of my brother.
I’m quite certain to still know the password, but I cannot remember the account-name. Any way of recovering it?
Do you still have access to your email address?
If so, reset your password. They will send you a mail with your username in it.
To add on to this, early steam accounts used your email address as the login name. So definitely try using that.