Yes, these are titles. Thank you for the screenshots, they do help clarify.
Your project is Vertical, and your Viewer is scaled up so that what you are seing is not the whole frame - on your last screenshot, note the small rectangle on the right side, with a red area in the middle.
The tall little rectangle is the whole frame, and the red part in the middle indicates the part that you are currently viewing.
If you go to the little menu at the top of the viewer and choose Fit (instead of the percentage that is showing there), you will see the whole frame. I am thinking that this does agree with what you see on export.
If you did not mean to make a vertical project, this can be fixed without having to redo all the work.