First, loose the stam gems 'cept for the 1 you need for the meta bonus. Secondly, you need more BV. Raid buffed you want to get as close to 3k as you can get. I looked through my logs and I'm just flat out blocking more than you, and the more stam you have also the harder leeching swarm is gonna tick for.
Getting a gnomish autoblocker so that you have either an extra 440 or 200 BV per round should help and in addition its a flat 117 more BV which will also help a lot.
Get titanium plating on your shield, that's another 40BV right there. Also it looks like you're probably decently over 101.6% with raid buffs as it is and once you drop the ony trinket and re-gem all stam you should be there no problem and this will increase your BV by at least 167, you seem to be just under the mark and remember with glyph of blocking that makes 167 10% better, so closer to 180 extra BV.
What I do for phase 3 is the second set of adds after the second burrow phase usually gets to me right as anub'arak hits 30%. For the first wave I don't use a trinket. Phase 3 is usually about 5 waves MAX for us, usually more like 4 (we often army of the dead the last one too). Therefore the first wave I can hit trinket 1, the second wave I can hit trinket 2, the 3rd wave I can shield wall and/or enraged regen, then the 4th wave trinket 1 is up again then the 5th wave trinket 2 is up again, or at least close to it. (to be honest I just have a trinket priority macro setup and then shield wall if a trinket doesn't pop).
Hopefully this helps, good luck! I know it can be frustrating, we had a wipe tonight where Anub'arak had 7k hps left.
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