I never get why people say Whisperer is hard, yeah it’s the longest of the dt2 fights but all you do is L movement and when it’s enrage phase you just circle around the boss if you can’t keep up with the L movements
Another thing I can think of being a problem is not using in game sounds to be able to hear the bosses attacks, that or you aren’t counting the bosses attacks during enrage (she uses 2 range at the start then 2 mage then 2 range repeating)
Edit: you’re also staying in the shadow realm for way too long, you need to memorize which pillars are 1/2/3 health when you enter and then exit immediately, same with the green orb patterns, however id give more leeway for staying in the shadow realm there when you’re first attempting this boss, and then ghosts just kill the 2 ghosts saying Vita and exit, unless you need sanity then kill the 3 saying Sanitas and exit