Well there are few things wrong with your skill build that when you fix, and once you do, you should see the vast majority of your problems just melt away. I am assuming that you want to tank as you are climbing that tree and you are obviously using the ion cell, if this is incorrect please post a comment! The other thing you will want to change is your gear priority, as tanks should be grabbing endurance gear instead of aim. Your fights will last longer but it will be almost impossible for you to die fight anything less than elites of higher level.
So first thing you need to do is go to the fleet and respec to regain your skill points, the respec guy is located in the training hall and is called the skill adviser. Once you have all those skill points in your hands, it's time to concentrate on the tanking tree. You should lose the blaster augs, the power armor, demolition and the heavy stock. Those are all great choices for your skill points, but after you have run up the tank tree as high as you want to go.
You do have a couple of decisions to make about which exact route you should take, mainly do you want to concentrate on close range or long? Each have different trade offs and neither is really better than the other so you should pick off your play style. Basically, if you like to move you should go long range and if you like to hunker down and bring them to you, go short.
The Short Range Build
The Long Range Build
So some analysis to back up the choices that I've made and that will hopefully guid your future choices.
The short of it
You are there to take a beating, but you want to hand one out as well. By increasing the skill points you spend on Stockstrike, you gain a lot of abilities and chances at blowing your most damaging attacks. You are basically going to close with the target and then unleash your taunts and grapples to keep the aggro on you and off the healer that is keeping you up. The 100% trigger rate on your ion cell means that you can hit the target with High Impact Bolt as soon as it cools down and that hit will ignore 60% of the armor... which is a big deal on some of those elites you're trying to kill. You also get pretty good endurance gains and damage reduction gains so you will actually stay up even taking a lot of dps. This build really does need endurance gear to make it sing as you have to be close and most elites and champions have some kind of knock back so you have to be able to survive the run back.
The long of it
Stick and move, stick and move. If you like to move, this build counts on you moving in and out of range of your enemies and using your long range abilities to manage the aggro. You need to be good at strafing and making sure you don't leave the area of the fight, because if you stray to far, the guys regen and you have to start all over again. That said, since you are using range and movement to mitigate the damage, you can wear less endurance gear and do a little more damage. You also write off stock strike and concentrate on your instant attacks and normal attacks, and you should use your channeled abilities only to restore agrro.