A lot of things affect your dps. Your rotation and gear, your group composition (litany, trick attack, hypercharge, paean, balance), the fight itself (amount of adds, vuln up/down buffs on the boss, downtimes, things that make you disengage). Do you have any fflogs parse? I might be able to point out some things if you do. However if your burst during opener is only around 1.8k probably you're either undergeared or your rotation is not very good.