Re: Catalog partially and randomly synced with disc. Have to find and sync A LOT. Help! :(

Thanks for the replies so far.
How did I build the catalog: I don't remember being asked to build a catalog. I think I remember it asking me to rename if I wanted; I didn't.  Upon reinstallation, I specifically watched for some direction like that but there was nothing.  All photos are on my hard drive (I back up with Carbonite); no external drive.
When I try to sync a specific folder (subfolder of "my pictures") - doing it because it says it has something like 3 photos and I know there are 300 in there - I click the folder, then right click it and then "synchronize folder" and then I highlight all the images and then import them.  (it takes several minutes per folder) 
If it's a catalog folder with a question mark (some of which are duplicate names of ones that show as having a few photos), I right click it and then "find missing images"; after that I have to sync it as I mentioned above.
There are some subfolders and sub-subfolders of "my pictures" on my hard drive that don't appear in the LR catalog at all.
I have watched several videos, including Julianne Kost's.  I think I understand how the catalog works: the photos still  reside in their original places on my hard drive but are located by LR.  Any new photo files I've added since installing LR, I've imported through LR.
Am I out in left field?
I really appreciate your time and comments.