It sounds like you guys just really need to go back to basics and read up on how the classes work in MoP. Try having your people talk to guys from the more successful raiding guilds on your server for tips even. I pick the brain of fellow Rogues in other raiding guilds from time to time to compare notes. Most are totally fine with chatting for a bit.
With your low DPS you really can't expect a kill until you can get 10-11 stacks. Currently you're only getting 8.
Also: You know that you do 50% more DPS by standing on the energy floor, right? Are all of your ranged doing that?