Level 37 Defense Guardian. Have had none of the OP's problems whatsoever. Kira's brother and the Sand Demon were a little tough, but nothing terrible. As others have mentioned:
Use your interrupts (Between Kick, Force Push and Stasis, you can pretty much interrupt till the cows come home), kill the weak guys first, and don't be afraid to use Enure and your defensive CDs to start a tough fight. I've found that if I pop Enure and Saber Ward to start, then use Warding Call when Saber Ward goes down, it works better than saving them, and if it's a long fight, it gives you a chance some of them again.
There are also some "worthless" abilities that people don't use that are actually pretty useful if you use them correctly, like Pommel/Opportune Strike.
In the Defense tree, you can get Force Clap which causes Force Leap to stun the target for 2 seconds. Jump in, pommel strike immediately (for no focus) and depending on how much health is left and the situation, Slash, Sunder or Riposte (if it's up) to finish it off. So if it's a group of a strong and two normals, have Kira attack one normal, do the above to the other normal (that 3 move rotation usually finishes it off) then just burn the last one down.
Finally, as a defense Guardian all the little things add up to help a lot, like Blade Barricade and Blade Barrier.
P.S. Needing your defensive cd's to kill an elite/champion isn't a problem. It's called playing the class as intended. And if you think Force Sweep is bad, I suggest you take another look. Also, make sure you are using the right stance for the situation.