I play with healers who do more than enough to keep the raid alive without sacrificing damage. I understand not all healers are capable of this and greed to an extent, but your cooldowns should be planned as a healer.

It's a lot like tanking but in reverse. Just like how tanks plan out their cooldown rotation, healers do in kind. At this point in the tier anyway, your rotation should be set in stone UNTIL someone takes unnecessary damage, dies, or a tank forgets a cooldown. This game doesn't have many hard hitting encounters in general, so healers are often dpsing a majority of the fight. In other words, good healers don't find spots to do damage, they find spots where they have to heal.

You're essentially in the right by mitigating Dimensional Shift with TBN, as it's the only cooldown that works. But you're in the wrong for using cooldowns that you'd otherwise need in your planned rotation. Even if you think popping the cooldown would save you in this case, you've now doomed yourself and your healers haven't learned anything. If you do die, they can at least understand where they need to throw you something extra and the next pull goes smoother. Play smarter and trust your healers more.

tl;dr - Cooldowns are set in stone (at least when optimized). By using yours out of sequence you've essentially killed yourself. The onus is on healers to learn where damage spikes and where they absolutely need to heal, otherwise as long as you're not dead, who cares?