I wonder if it's your Photos library (if you have one)? If you look in your Pictures directory, there may be a file called "Photos library". Check the size of it. If that's not the case, maybe a tool like Omni Disk Sweeper or similar can pinpoint more about where big files are.
.CR2 files are Canon only, so if you shoot a different brand, you will have to search for those extensions as well (.nef, .arw, etc.). Also .dng files for an alternate version of raw.