Rage generation has 2 components, hit (your hits actually landing) and haste (how often you swing).
The big thing is your hit is only 9%. This means you're going to miss ~18% of the time. This can lead to some bad miss swings, and with a long swing timer (3+ seconds) this can lead to periods of rage starvation.
That's the gearing issue...
The other issue is probably your ability useage.
You can't use HS willy-nilly anymore. Your rotation is BT -> RB -> BT -> <slam/free GCD> with collossus smash on CD (well not always, sometimes fight mechnics mean holding off, e.g. right before some movement).
HS only when >60 rage.
That's probably as much your problem.
Also DBW and WFS are not very good at 85. You're simply giving up too much in the way of ratings (well I don't know about DBW's proc - but definately WFS) - quest rewards were probably better 2 or 3 zones ago. Same and moreso for the rep ring.
Quick upgrades can be had by getting your rep to revered (even friendly opens some upgrades) - and buying the items from those factions, that will help with the rating points.
The # of rating points needed per 1% is much steeper now than in WotLK - so when you go from 84 to 85 you're going to see a major decrease in hit levels.
Finally - I would suggest reforging everything to hit and if not hit then haste if your rage is your biggest issue - haste isn't a top stat for DPS according to the numbers Thegreatme and others have run - but it is useful until you feel 'comfortable'.