I would take 3 points from defensive stance and put em over in the arms tree. And then you want to take one more point out and get imp. shield block. You dont wanna go without that one. I would take that point from imp. Taunt.
Are you using the right rotation and abilityes ? Im asking as I have been taking kara all the way through, from when I started in there. Without the 3 more points in arms, and had no problem holding agro.
May ofc also be an issue because your dps overgear you ? Just some thoughts.