[SavageBT]

Pretty much everything Doogless said. Use the bloodgem and either VST or Xi'Ri's.

With the 'on use' trinkets activate them manually when you will be reapplying all of your dots in it's duration - these are your highest damage per cast time spells, and will get the most out of the trinket's use.

Even if you are using full FSW and the orb of the soul eater offhand and a soulfrost enchant still cast immolate - the damage it puts out for only 1.5sec cast is much higher than shadowbolt. Lifetap/dark pact only once your dots are applied but not when you have a trinket active, lifetap/dark pact early so that you're not oom when your dots run out. It's better to leave a dot inactive for a second or two than overwrite it or be inactive yourself - as stated use the time to lifetap or start a shadowbolt. The only time it's good to renew early is when you will be away from the boss and unable to reapply - use your judgement here.

Going down to improved fel armour will only ever get you +30 damage. This is about 2 extra damage on a corruption tick. Spend your points in destro - ISB helps ALL shadow users, yourself included. Bane is probably one of the most important raid talents, considering how large a portion shadowbolt is of even an affliction lock's dps. Keep devastation - 5% crit is 5% crit whether you are on 10% or 30%, its still 2.5% more dps on the shadowbolts, and more ISB procs. Destructive reach is of course for the threat reduction but I can think of plenty of fights where staying at 30 yards is dangerous, repositioning to spam SB loses you dps time as well.

I guess the biggest thing here is hit rating - I can't see your armory but if you haven't already use veiled noble topaz' in every yellow/red slot, and make sure you complete any set bonuses that give you +hit. Recheck your hit with the bloodgem equipped, and add pointes to suppression until you're at 16%. As your gear improves start removing points from suppression until you have flat 16% to hit for all spells.

BTW can you link a WWS of a fight or two with you and the other locks, let us know what else was in their groups (ele shammy etc), and maybe even some armory links. Could simply be the difference between hit ratings, more favourable groups or even the lack of the use of CoD on your part.