stamina gems aren't great for dps. get a nightmare tear instead, a plus +20 str gem is better in blue sockets after you socket one nightmare. pvp gear is bad for dps in pve. delete gearscore!!! You're also under hit, getting the MoS trinket willl help until you get there via gear.
farm PoS for the malykriss bracers and there is an 213 ilevel cloak from the badge vendors that will give you more dps than your current one.
are you standing behind the boss/trash?