As a healer, you are experiencing the blow back of the same problems I discussed in my tank topic. Namely that tanks in TOR are currently too squishy and can't hold aggro worth a damn, especially when engaging groups of enemies. This applies to both player and companion tanks. You really don't start to progress to any sort of useful tank functionality until the mid-30s (and even then groups are still problematic). The best I can suggest is to always be at least a level above the rated level for any story quests by doing side quests and any other form of XP harvesting (exploring the map, doing space missions, etc). Hopefully that way your companion's stats will be high enough to survive.
Aggro is still a real problem though. The best you can do is make sure your companion has any taunts they have enabled and employ any stuns or similar abilities you have to try and tie up one strong/elite enemy while you dispatch the swarm of weak/normals. Consular Sages (and I assume their mirror Inquisitor Sorcerers as well) have a very useful ability in this regard - Force Lift - which they get very early on. Do Smugglers have something akin to that?