I am creating a baby announcement for a client and am having troubles with Photoshop. The images included are high-resolution, since these files are going to be sent to the printers. When saving the file as a JPEG at maximum quality the file ends up being much smaller than the original images. My high-resolution images are sized between 14-15MB. After saving in Photoshop, the jpeg file size is 726KB. This is quite a significant drop and I cannot send this file to be printed. I have tried starting over and recreating the announcement. I have tried using a Photoshop template. I have tried exporting my images again. I am at a loss. I have no idea what to do next and no idea how to fix this problem. Again, I have high-resolution images that I am putting into a Photoshop file and wanting to save as a JPEG file to be sent to the lab to be printed.
As well, the Photoshop file (.psd) itself is 33MB.
This is jpeg data compression. It doesn't affect resolution. You can check that in Image > Image Size.
The more aggressive the jpeg compression (lower quality number) - the smaller the file footprint in MB.
Jpeg compression is destructive and cumulative, and for this reason you should avoid using jpeg as a working/storage format. It should only be used as a final delivery format to save bandwidth.
You say both "save" and "export" but these are different things. It's probably worth describing what you do, and what settings you choose, so we are all on the same page.