I do not understand what you have written expand and stitches. What is stitched? Can you post a screen capture the show Photoshop UI palettes and image window?
Try using Canvas Size the expand the canvas the no need to use crop or duplicate the background layer. Empty canvas is easy to add to the background. You can add canvas to 1, 2, 3, or 4 sides of the Canvas with Canvas size you can also crop with Canvas Size, with one canvas size step you can crop and add canvas.