I'm trying to send my smart previews and catalog to an editor and the two files have a different number of pictures. Lightroom Catalog has 2,811 and smart previews shows 2,719 so it seems that I am missing some pictures. any idea what might be going on?
Your are not missing pictures. There is no law that says that each picture must have a smart preview. Smart previews are only generated if you tell Lightroom to do so. Apparently you did not tell that each time pictures were added, so some of your pictures do not have a smart preview. That is perfectly normal. The easiest way to generate the missing smart previews is to select all images, and then choose 'Library - Previews - Build Smart Previews'.