I have to agree with Brightamethyst, whereabouts in the main story are you up to? If you're not yet up to EW's story, you could try running earlier dungeons through Duty Support, which are NPCs - Duty Support is actually quite useful for learning the mechanics of dungeons as the npcs move according to the mechanics so you can just follow their lead.

But yeah, level relevant content is unlocked by completing the main scenario (and the EXP the quests alone give will probably overlevel you), so go back and pick up the main scenario from where you left off and just follow it through (if you're not sure where you are up to in the story - there should be a guide in the top of the screen that lists the current main scenario quest available or active and where to go, but if you don't have this, just open your journal and see what your last completed story quest was, as the next one will be available at that same npc or nearby at least.