My game's working now! It seemed to be a driver issue, I downloaded the GeForce Experience and did some updates there, downloaded more updates following this post:

https://www.reddit.com/r/ffxiv/comme...nd_wmvcoredll/

and re-installed the game.

Not sure how the game used to be able to run if my drivers have always been outdated, but I'm just glad things worked out. Thanks for all your help!