Mac 2012 Mini, Photo Problems

2012 Mac Mini running Hi Sierra 10.13.3. Hi i am running my photo library from a Sata 2TB internal hard drive after moving it from my main hard drive a few months ago. I thought i had done everything OK and checked it all to see if the library was copied over, which i thought it was. Checking the "about this Mac" today and clicking on storage it says i have a 50 Gig photo library on my 2 TB drive and for some weird reason 100 gig on my main drive so something is clearly wrong. I went into to my hard drive where the "apparent 100 gig file is and cant even find a library at all or the so called photos. Excuse my novice question but i'm flummoxed and need to free up the space on my hard drive PDQ. many thanks in advance.