Help with iTunes Library

OK, I'm no iTunes rookie. I've had my library for 8+ years and have migrated it through several PCs, to a Macbook, and recently attempted to move it to a NAS drive (WD MyCloud) since I got a new Macbook with a small SSD. I have a large library (450+ GB including the mobile applications folder), and the move did not go well.

I think I did it correctly (changed media folder location, consolidated library), but I had tons of broken links (iTunes didn't know where the files were, despite them being in the correct location in the media folder). I also occasionally try to play a song, and the song that plays does not match the song title. I have tried numerous things to fix it (recopying the files, findtracks script, deleting the plist file, etc) with very limited success. My iTunes media folder seems to be a weird hybrid of the old and new structures. I have my music in /iTunes Media/Music/ but when iTunes tries to organize the library it starts moving my music up a level to the /iTunes Media/ folder.

Any help here would be greatly appreciated. I've put a lot of work into ratings and playlists, so I would prefer to keep them... but I'm so frustrated at this point I'm also open to rebuilding the library and losing them if I have to.

I would have given up by now, but I have several iphones and ipads that sync with this library.