Am I out of my mind with the endurance thing?
In a word, yes. For a couple of reasons. First, the damage absorbed by force armor is based on your willpower rating, and the size of your heals is based on your willpower and power ratings. Second, in a long fight if you have to use noble sacrifice to regen force, the cost is a % of your max HP, which means you will be doing more damage to yourself in raw numbers.
As a healer, you will draw agro from every mob that is not controlled, taunted, or being attacked. If you are solo questing, CC the strongest, and turn off your pet's AoE attacks. In flashpoints, bubble yourself and the tank, and the DPS if there are multiple non-CCd mobs (ie, an AoE heavy pull). Then start healing when the bubbles go away.
Nadia is pretty fragile. I leveled with her at the end mostly because I wanted the challenge....but I usually ended up having to bring out (and re-gear) Iresso for class story bosses. If I were to do it again, I would just use Iresso and switch his stance and offhand depending on the fight.