As others have said, that dungeon is a nightmare to heal in pugs. Even veteran healers have trouble with it, particularly if it's a bad party.

My advice would be to seek help with it on Duty Finder. You need a party that can do the mechanics. Of course, as healer you also need to be sure you can do the mechanics, as mechanic competency is critical to playing healer. However, it sounds like you are.

If you want to make that dungeon easier, mechanics-wise, I suggest NOT moving to the gap in the knights immediately. What happens is that the AoEs spawn under all the players, as the knights start to march across. The #1 wipe issue in pugs is that people block off the safe spot for the knights by all moving to the safe spot as soon as the knights appear, causing the aoes to spawn on the safe spot. This is particularly bad with the chains, because the chained members need to run diagonally. One player needs to go through the safe spot and into a corner, while the other needs to run into the opposite corner away from the other player and the knights, before coming back to the safe spot. If the safe spot is blocked, the chain doesn't break, or the DPS eat knight damage trying to break it horizontally.