Took a look at your logs from your H Krosus fight and it appears you are not taking advantage of one of your main AOE spells: Healing Rain. Krosus is basically the easiest fight for shamans to heal because its just massive raid damage. That being said, you should ALWAYS have healing rain on cooldown. I took a look at my H Krosus logs and found that Healing Rain accounted for nearly 10% of my overall heals with chain heal at 23.38%. For you, healing rain was only a mere 3.78%. I did take a look at your raid combination and having two resto druids will definitely reduce the amounts of heals you do on a fight like this (due to tranq and wild growth). However, like I said, you should probably try to use healing rain more often as well as cast more!
Also, I’d recommend moving away from CBT and try echo instead. CBT is very situational and you have to be good about knowing when the raid is taking damage and using the totem at the correct time. I personally think it is a waste of mana and would rather have two riptides and take advantage of the riptide buff.
Hope this helps.