I can't find an answer this so I wanted to see if anyone here could tell me:
Me and my girlfriend use the same account and we each have our own world state. How do we make use of them for our respective play throughs?
Could I start a game with my world state uploaded and then let her upload a world state when she starts her game? Or would that cause problems with the game?
Yes, if my understanding is correct, you'll be fine.
When you hit the "Export" button, your World State goes into a kind of "buffer zone". You can only have one World State in there at a time so, when you fire up DA:I, that will be the only World State it will find.
Before your girlfriend plays, she should go into the Keep, load up her own World State and export that into the buffer zone. Yours will be deleted/overwritten (not from the Keep, just from the buffer zone!)
When she starts a new game in DA:I, her World State will now be the only one in the buffer, and so that will be the one that DA:I imports.