where is my photo library?

I was trying to make a backup copy of my photo library, when I go into Photos > Preferences > Show in Finder it takes me to the file user > Pictures > Personal Photos.photoslibrary, but the date on that doesn't reflect the changes I made today (or since May 12 for that matter):

When I try opening it to see if it contains the changes I made today I get a warning that says this is the first time I'm opening it. So, if this isn't my photo library, where is it?