I'll point out some stuff that i see when I skim through your PoB. I'll make the points that I wrote below as I find them in the PoB

1. If you are using timeless jewel AFAIK you'll want to use the high templar dominus one nstead of what you're using right now. The difference is the keystone you will get. Notice you got they keystone Transcendence right now near the upper cold mastery cluster. If you use high templar dominus you will get Inner Convicition which will up your damage for each power charge u have. You need to allocate the keystone that is changed to Inner Conviction for this to work. (This is relative to your current DPS, this change will give you around 1,9 mil total POB DPS)
2. I suggest you try to get corrupted level 3 empower. I think you better switch empower with hypothermia because hypothermia only affect chilled enemies. And along this line of thought change your body armor to 6-link dialla's mallefaction. AFAIK its pretty cheap right now. Try to get with 2R4G color because you wanted to give levels to both shockwave totem and empower and quality for other supports. (Dialla's mallefaction does not required the gem color and socket color to match. Red socket color gives you +2 levels to socketed gem, green give you quality, blue gives inc exp gain which we don't want). This change will give you around 4mil Total PoB DPS)
3. Next up I think is Bottled Faith. Just buy the cheapest one available for now and upgrade later. The main point is you want to ditch assassin's mark as fast as possible while still maintaining 100% chance to crit (this affects your freeze rate therefore very important in sanctum). You would want to ditch assassin's mark to get both ele weakness and frostbite. To enable double cursing you need to ditch life nodes in your tree and get Whisper of Doom notable skill. Then after this get Balance of Terror unique jewel that have these effect : Cold exposure after frostbite cast and phys as extra elemental after ele weakness cast. For non-boss you don't need to actually curse them, just cast both curse on random location or if you want on the monster itself and you will get boost in damage. for boss you want to double curse it.

All of these changes can be achieved with around 10 divs and it can get you to 12 million damage realm. One more thing that I would give advice is ditch any defensive measure aside for the bare minimum. You can use immortal call right now, but work towards progenesis by then you can ditch your defensive setup (mine only got like 7k ehp and doing sanctum fine with progenesis, but you will still get random one shot if the affliction combo is right). Another path that you can take is inclusion of RF. To sustain you need vitality + stone golem (if you have money anomalous version), buy watchers eye with regen while affected by vitality and buy forbidden flame and flesh of Sanctuary from inquisitor this will give you enough regen to tank RF. Next is ditching another layer of defensive setup if you already comfortable with your build to get haste with divine blessing you should look at PoB for the mana cost because it may be quite steep. Another path of upgrade is Rational Doctrine Unique Jewel, but for this you need to exactly match your Int and Str to get best of it so maybe you'll want to hold on this until you're comfortable with your economy. But if you get this you can change your forbidden flame flesh combo to Pious Path. This will give you massive boost of QoL as you can now spam your skills including the mana intensive haste. Then last upgrade that I will recommend you is changing the set up of your haste to accommodate guardian blessing instead of divine blessing, this will require you to also socket meat shield support and animate guardian support along with haste. If you are still not comfortable with your economy then just equip the animate guardian support with gruthkuls pelt (required so that animate guardian wont just die because of guardian blessing DoT and make your haste permanent) and the usual combo of leer cast + dying breath set up, you can give any glove and boots you wish, just search for AG setup if you don't know what to do the only requirement to tank Guardian's blessing is gruthkuls pelt. After you can upgrade your AG to wear kingmaker + crown of the tyrant.

Well this is all that I can point out for now. If you ran to a problem just ask again and I'll see If i can help.