Your spec is good. Staying alive as a sage healer is tough if you don't have guard on you. If you have any tank friends or guildies, ask them to come along and guard you. If you are pugging it, either tell the grp you are heals and ask for a guard, or throw down a salvation during pre game so everyone sees you are a healer.
Whether you get a guard on you are not, you need to hug a pillar or something you can break line of sight with, try not to stand out in the open. A Knockback followed by a slow can help a lot here too. Always try to heal from range and out of sight as much as possible, because as soon as a maurader or powertech sees you, he will force leap right to you.
As far as the rotation goes, i don't really use a "rotation", its more of a situation priority list. I use Rejuv about every time its up, mostly to get the resplendence buff, plus it is instant cast. If you are getting interrupted a lot, try using mind crush or something with a cast time first, so they interrupt that, then cast a heal. So maybe try something like Rejuv, mind crush, when they interrupt that go for the fast deliverance.
Anyway hope some of that helps.