Alright, I see some of your points mentioned that resulted in a few conflicts, which resulted in your unfortunate experience.
Get more spirit, and stop using flashies.
At this very point, G-heal > Flashies. G-heal costs less, and fortunately heals more. What's unfortunate about G-heal, is that it's spell cast time still remains high for dungeoneering. If you can time G-heal just fine, then you will manage a bit far. Only use flashies as an emergency heal.
You haven't mentioned CoH at all. CoH is a spell that should be used on cd regardless, including pom. costs about 1/2 of flashies, and are smart heals. Smart heals > Your heals.
Use Renew as a mitigation spell, you want to toss out as many renews as you can for those whom are constantly taking damage. Haste is supposed to add more renew ticks; not sure how this will work or if it will be even helpful vs being full overheal. Plus, now that our haste has been wrecked, slow renew ticks = terrible. Not saying that we should rely on getting more haste for faster renews...
Cleansing people is a must. Healing through them will just burn you mana while you keep healing.
Lightwell > Renew. Here's the hard part, people tend to put their eyes on the meters or tunnel vision the boss. The key to get lightwell going is to notify. I made a macro called <CLICKERS CLICK LIGHTWELL> and just spam the hell out of it to get people's attention, or just yell my lungs off in vent. (:
Mana is what's killing us. There is a blue post mentioned somewhere about priests being in a pickle at the moment, so really, just drink per mob pull like I do.
Make sure you s'fiend during lust, and hymn of hope right after you s'fiend. HUGE amountz of your mana will return. In most cases, slothful & blockheaded people WILL BE the cause of your mana being drained. Tanks not putting cds, or dpsers not putting in their A Game will be the cause of the upper-most QQs.
Chakra Heal w/ it's chastise effect > Chakra POH w/ it's chastise effect. The healing from sanctuary (chastise effect from chakra poh) is just not worth it. Heals incredibly low, and the chastise effect from chakra heal (serenity), is awesome. 25% increased crit chance, anytime baby.
In terms of stats, crit loses a lot of value. Holy Concentration and Surge of Light (if you even spec SoL) are not going to proc off crit anymore; SoL will proc 6% off of Heal/Smite, and Holy Concentration is a passive Mp5 buff. The only thing crit will do is affect crits on direct heals (but not the HoT portion of renew) and Inspiration uptime...
I think I will be removing half the crit my gear has, and start switching it to Mastery. Mastery seems like it will be our go to stat. If they come out with mastery gems, I will probably look at regemming mastery or INT/mastery.
Plus, Cata has been out for what? Less than 2 weeks? I'd give this some more time before "hanging out my robe" In the meanwhile, the object is to gain more spirit, gain more gear.