Just bought a new light fixture for the vanity. Took off the old 8 light strip to find two 6-8 inch holes in the drywall (my thanks to the stupid builder who didn't install the original light correctly). So, obviously, I need to replace a section of drywall. I don't have any studs behind these 2 holes, so I assume I need to cut a hole large enough to find some studs. Can I buy a small piece of drywall, or is it only sold in large sheets? Has anyone else had a similar experience that can offer advice on fixing this wall appropriately ? Thanks