Just from looking at your armory, your gems are all over the place. IMO you should be using:
Red: Int + Crit
Blue: Spirit + Crit
I used to gem pure Int but I switched over to a Crit build and it has increased significantly. I lost about 500 Spirit but gained about 7% Crit.
You should reforge:
Haste 7613 > Crit > Spirit > Haste => Mastery
Your gear probably isn't high enough for the 9k Haste breakpoint unless you gem for it, which I don't recommend. Haste at 7613 will give you an extra tick of Healing Rain with 5% raid spell haste buff.
You want so much Crit because with every Crit you put out, you get mana back due to Resurgence (one of your passives).
I would recommend dropping Glyph of Riptide for Glyph of Chaining. Chain Heal is good glyphed because it's only a 2sec cooldown. Between those two seconds you will be refreshing Earth Shield, casting Riptide, putting down Healing Rain, so the 2sec cooldown should not be a problem. Honestly you shouldn't be spamming Chain Heal the entire fight anyways, because eventually you will go OOM.
Can't really help much more unless there are logs. Just gonna post some general tips:
- Make sure to Unleash Elements before you Healing Rain for the 30% buff.
- Drop Healing Stream Totem on cooldown.
- Know the fights well enough to predict when to use cooldowns. If you sit on your cooldowns, you'll never use them.
- Make sure to use your Fire and Earth Ele to buff your heals by 10%.
- Keep Earth Shield up since you have 2pc (it should be up regardless, but sometimes my 2pc is my second highest heal if I have really high Earth Shield uptimes)