Actually there is a Quest that will show up in the Quest-Tracker "Travel to Barbiron" or something like this and if you click on it, you auto travel to the Warp Portal to Barbiron. (i did that quest on a low char of me a few weeks ago)
I think if you miss that quest, you might have to check your quest tracker if you really did all the Mainquests.
The Quests you need are:
"2. To go from Mereholt to Barbiron; Complete the L27 Main quest line, in Mereholt, starting with Subduing the Earthborne Maulers and ending with Greenback Grizzlies and be L30+ to advance"
Quick Quest Guide - DrDieLess
Greets