Just found out something quite important today - you really do need to do all the quests at Orebor in Zangarmarsh if you want to do much in Nagrand.
Quite annoying really, as I thought my lock had finished in Zangar as far as levelling was concerned. Still, at least it was easy, although I mistook one boss for another, so ended up killing an elite twice for no quest reward - all I got out of it was a ghost mushroom, plus a little xp.
Then I went upstairs - I was in the Ango'Rosh Stronghold, and killed the boss I needed to, which surprisingly was easier than his mate in the bowels of the earth.
Now I have Terrorclaw, Mragesh and collecting venom to look forward to, as well as the Underbog quests which have been in my log for weeks now, then hopefully I can go to Nagrand and do some more questing.
I hit 68 as well, so although it has taken me ages, I might get to 70 sometime in the next month or so - I have got a 2 week holiday coming up, and its taken me nearly a year to get this far!