I created my Gmail account as firstname.lastname@gmail.com (by mistake), but I always create accounts on website using firstnamelastname@gmail.com. As a result

I created my Gmail account as firstname.lastname@gmail.com (by mistake), but I always create accounts on website using firstnamelastname@gmail.com. As a result, I often have problems when communicating by email with companies, as they can't match origin of the email (firstname.lastname@gmail.com) to my account email (firstnamelastname@gmail.com).