I've played through prophecies a few times and enjoyed it thoroughly.  I recently received Nightfall as a gift and have been enjoying that as well.    However, I have completed every quest I can find, have done only 3 or 4 missions, and have run out of things to do.  I can see on the map there is a huge section that I've yet to visit, but I don't know what I have to do to get there?    Has this happened to anyone else?   What next?    If it matters, I have almost reached the rank of commander.
 
EDIT:  According to the map I viewed online, I've gotten to and (as far as I know) done every mission in the southern island/continent.   I can see the other, larger continent to the northwest, but don't know how to get there.    The last city I quested in was Blacktide Den, and I've been to and thru the Mehtani Keys.   I currently have zero quests, done every one I could find.