Go to your Google Account. On the left navigation panel, select Security . On the Your devices panel, select Manage all devices. You'll see devices where you're currently signed in to your Google Account or have been in the last few weeks.

Another way to find Gmail email address from the desktop website or the official Gmail app is to select your profile image at the top right. If you're on a computer, this shows the email account you're using right now and any other Google accounts you're logged in to in the current browser session.