Your gear is plenty good enough to heal ZA/ZG. The questions you have to ask yourself are:
Are you using proper spells at the proper time?
Are your DPS/Tanks taking far more damage than they need to be?
Your reforging does pretty much cancel itself out in terms of mst & haste. Maybe try reforging all of your haste to mst and see how that goes - and all of your mst to haste.
You can also try a spec like this: http://www.wowhead.com/talent#bchZfurrR0rkfzob
as Veiled Shadows is not going to help you in 5 mans, but I assume you have it for raiding.
You also have 2 empty Major Glyphs - which could be CoH (pets can snag CoH ticks).
Are people using Lightwell enough to warrant the 15 charges? Try Guardian Spirit instead as it may give you that extra CD you need to keep your tank alive.