I too am struggling to learn a new 80 warlock. but I have made a lot of improvements thanks to the warlock discord. my gear is still not great but I am improving although I seem to top out at about 4.5k dps. I have a long way to go but I am not ready to give up yet.
have you tried simming your gear with 0 raid buffs then comparing it to a target dummy? I found my dps was not that far off from the sim, so gearing is a big issue. I imagine your pvp gear is hindering you more than you think. wowsims is your friend