By "all the guides," do you mean those found at Noxxic and IcyVeins? If so, shame on you - that's your number one problem right there. We have a good sticky here; read it.
To your gear, you are over capped on hit and expertise; to be fair, not much you can really do about the hit with a Feather, but you're still forging into expertise. You're using pure stam gems and pure strength gems when, at that item level, you should be using haste/strength orange gems for red sockets and either haste/hit or haste/stam green gems to match blue sockets (the haste/stam gems are really only useful if you are desperate to control your hit). Also, you're using a prismatic gem, something which has not been useful since Wrath; should use pure haste gems in prismatic sockets.
Boot enchant should be haste or Pandaren's Step - and I would recommend Step as you're specced Long Arm; the 8% passive speed boost may not seem like much, but it still helps while Judgement is on CD. Gloves should be strength, chest should be stats, cloak should be crit. Need to get your blacksmithing up to add sockets to gloves and bracers.
Most important gear-related flaw, looking at your LFR experience, is that it appears you've been padding your item level at the expense of set bonuses. Normal T14 set bonuses trump 522 off-set gear, and the LFR 2pT14 will still trump 522 but I don't think LFR 4pT14 would be that valuable. Our set bonuses have been really, really strong this expansion - to not have them is to do yourself a disservice. Also, Darkmist Vortex is absolutely terrible; replace ASAP.
To spec and rotation, Execution Sentence is the strongest talent, single-target, at L90. Light's Hammer is only better if you can guarantee 2+ targets to stay within its area of effect for at least half its duration. If you're not pairing Wings and HA, that's a problem; when it is available, pop Guardian and wait 11s, then pop both Wings and HA to use all CDs to maximum effect.
Dont use pvp gear for pve and wonder why you dps is low or tank gear or stamina gems/enchants...
PvP gear is actually fine, as PvP stats are not factored into an items stat budget; PvP is also the best way to quickly acquire a decent weapon.