I dps what I sim, sometimes higher. But I've got all these items that seem like they could up my dps. But I've tried every combo and sim'd like hell w/o improvement.
Even if I were to get a full 4set, it's a dps loss, which is fucked up.
The armory seems to be messed up right now, so I can't run you through ShadowCraft.
A few things:
Assassination is probably better for you right now since you only have LFR AoC and a 536 MH. Once you get mostly normal SoO gear, Combat will probably swing back into favor.
The T15 4pc for Combat is insanely good, but only if you have awesome ping (<20ms) and fast hands. It sims well because these things are assumed; however, if you're energy capping in practice, the set is nearly worthless and should be replaced once you can get the new 4pc (with mostly flex/normal pieces).
Almost nothing from LFR is going to be an upgrade for you. You need to get stuff from Flex for minor upgrades and normal for large upgrades.