The main thing I want to stress in addition to what the previous poster said about interrupting, defensive stance and using your defensive cool downs, is Strength. I'm seeing a lot of Guardians stacking as much endurance defensive stats as possible. This is great for group settings when you are tanking, but you'll do absolutely no damage.
I was having the same problem as you guys but I was interrupting, using cool downs, etc, but the fights were marathons and I always ended up dying. In my opinion, you want to try to get a nice balance of Strength heavy pieces in your gear to try to maintain a balance of the two. You can defend all day but if you can't take down the enemy, eventually you will die. You have to be able to put out some dps when you are leveling, as well as PVP. I have switched from stacking total endurance to having some pieces focus heavy on dps. If you notice, you'll get plenty of endurance with your pieces(relics, belts, etc..), no need to stack it even more (again, unless you are trying to tank flashpoints and raids and what not, in which case I'll just build a separate gear set). Plus soresu form should be plenty of defense for you.
Again, try to keep a healthy balance of offensive and defensive pieces. Just because you're a "Guardian" doesn't mean you have to swing a whiffle ball bat...
Hope this helps.
Tenball