Newbie who messed up.

[BuffaloJim]

So during the mysterious letter quest I neglected to go back to Amarissa's cell. I have completed the quest and unfortunately saved since. Did I mess this up entirely?

 

[MikeB]

No, you didn't mess up anything. She wouldn't have been there anyway.
Just make sure to enter her empty cell once (you can always return to the Unknown Dungeon) to advance the "Where is Amarisa?" quest.