I'm sorry that you're having a difficult time.
I wouldn't say that I'm a one-man army, but I can comfortably beat most people that I encounter in a 1v1 situation, with the Marauder/Sentinel and Ops/Scoundrels (who get an opener) being the hardest for me to tackle. I've even pulled some 1v2's off, which is pretty fantastic because I know I'm not that good.
Generally, I find the ranged classes to be easiest because they're so busy trying to keep me out of melee range that they crumble.
What kind of suggestions do you have that might improve the situation while maintaining balance?
Because I'm pleased as punch with my Vengeance Juggernaut.