You're maintaining ISB, not Purifying much, dying to Stagger DoT, and getting few Gift of the Ox orbs. Those things are related.
You should be using ISB to maximize how much Purify clears, not solely for the smoothing.
You have a large health pool: use it. If you're above 75% health, using ISB is probably a waste. It's smoothing when you don't need smoothing, and it's reducing the number of GotO orbs that you're creating.
Gift of the Ox is absolutely massive, but it requires actively playing around your health pool to maximize.