Well to start, where exactly are you having threat problems? Is your issue with aoe packs, single target threat, or both? What rotation do you use for aoe threat? What rotation do you use on single target threat. What glyphs do you use?
Too tough to say what your problem is without at least the above details. Your gear looks sufficient to hold threat. As for your spec, I would really consider speccing into KM as it is a pretty sizable sort of threat for Frost Tanks.