The reason your sci doesn't find any love in STF is because those missions are mostly a DPS race and hardly anything is needed.
Even more so now that the Birg have been nerfed again and can't generate criticals anymore.
So people are even less likely to die.
You need to find your niche in STFs. Something that really helps in taking things down faster.
I found mine with aggro tanking. I put out barely enough DPS, but I make things shoot at me, which most capable players should recognize.