Honestly it could have been a bit of everything, if you were spamming cure2 with regen and occasional emergency cooldowb like tetragram you should be fine. Which means that it's either your tank not being careful enough, dps not dropping things fast enough. I don't believe your gear is the only reason, it could have had an impact of course, but increasing your healing by 20% will not make things go from “barely manageable “, to "cakewalk"