Gmail's Conversation Threading function often lumps emails from the same sender all together. Sending multiple test emails to your Gmail will likely cause the emails to be grouped together and appear with a number next to the From name. Clicking the From name or Subject Line lists each email - but only the top email will display its contents.

The content of the other emails is not visible because Gmail does not detect that the "conversations" have changed overtly. To see the content, simply click "Show Quoted Text" in each email.

To avoid this in the future, delete any copies of the same test email before sending again so that there is only one test email in the inbox at a time.