You're missing quests if that's been your experience. On my Sorcerer I've always been 2-3 levels again on a planet, my quests were always green or 1 level from going green, all the way till Voss where I caught up to my level but I found out later that I accidentally skipped the Alderaan bonus series so that's why. Oh and I haven't done any FPs, no PvP and 1 space mission. I only did Heroics when I could easily find a group for them.