Also, to track absorbs, Options-Panels-Hots, and check Shield Status. Should show you a circle over the icon when the shield is in place and there's still absorb left to spend.
It you cast it on others and not on you, you won't see this circle on yourself and should be obvious that you have no absorb effects on you.
If you do cast it on you, you should see the circle meaning you got absorb up for incoming damage.
If you do cast it on you, but dmg goes out and the absorb effect is spent, you won't be able to differentiate between when you still have the buff but is spent and when you have the buff cause you're casting on others. But in that scenario does it really matter? Absorbs is what you want to track, no?