Survive bigger pulls as BDK

I'm having a bit of a crisis where I heavily question my ability to tank, but I also can't see what I'm doing wrong. But just to be clear, Im not denying that I very well could be doing something wrong, I just don't see what.

I have been tanking on and off with BDK since shadowlands, my highest rating was 3,3K.

I'm currently doing 12 keys and I really struggle with bigger pulls, for example NW, pulling the first 2 larger packs + 1 gatekeeper.

I know that blood death knights are notorious for being weak at the start of pulls, and I often have to use 2 defensives just running into a larger pull (IBF+vamp blood for example, and usually rune tap too), but I also struggle during the pull which really brings me down. As long as I can keep defensives up, Im usually good, but after I run out of DMG reduction CDs, even with boneshield charges, I just have to spam death strike (literally spam), and as a result, I run out of RP. Switching to heartstrike to get runic power usually gets me killed because my health is going down so fast that I just can't afford not to death strike.

I don't face my back to the pack while tanking.

My Ilvl is 634, so there is a bit more stats to gain but is it really such a huge difference? Given that I struggle so hard with my current situation.

I do however have some keys (rarely) where everything just goes so smooth and I feel like I can breath during larger pulls. But since it happens so rarely, I'm starting to feel that maybe it's a super good healer that just carries me through a pull that I shouldnt be able to survive normally, rather than me having bad healers the other times. Besides, I don't wanna say that "it's not me, it's them" when this happens so often in keys.

Smaller pulls / normal pulls and bosses works just fine. But in bigger pulls, I just can't handle it most of the time.

Another example of a pull that is impossible to survive for longer than 15 sec for me is pulling more than 2 packs after the second boss in COT.

I have tried to watch high rated players and sure, their HP goes up and down, which is normal for DKs but not at all on the level that it does for me, they at least have time to build back RP, which I feel I don't have.

What am I doing wrong? Am I just not cut out to tank?

Here is an example from first pull in NW;

DND on the first pack to slow them and get aggro > IBF + Dancing Rune Weapon + Rune Tap while pulling second pack > abom limb and run to gatekeeper > at this point, my HP has dropped to like 10% and I dont have RP yet so I tomb stone to get some time to heart strike > my HP is stable after a while and we lust and I cycle through what I have leftn in defensives, but I often need to combine 2 because I feel like I'm taking too much DMG otherwise (for example rune tap + vamp blood) > I use whatever I have left and after Im all out, I try to kite but usually dies while doing so after a little bit since the mobs eventually reach me.

I saw a clip with Yoda pulling even bigger than this in NW with a BDK and I just can't understand how it's possible. Am I wasting too much CDs early on?

Any tips or thoughts are greatly appreciated!