As far as that screenshot goes, right away I see that your primary attack has a penalty of -2 because you're wielding a 2 AC shield, and rogues don't start with the Shield Proficiency feat.

As for the two-weapon fighting, with two longswords equipped, you will suffer a -4 attack penalty for all your attacks; your two main attacks, and your off-hand attack. You can get that down to -2 attack penalty by putting a light weapon in your offhand, (like a shortsword). I'm not sure how Power Attack would work in that case, since the rules say Power Attack can't be used with light weapons.

And, like has been said, power attack can drop your attack bonus. In this case, you could get up to -6 attack penalty. So if that's stacking with your -4 attack penalty to give you -10 to hit... yeah that'll be rough. Take note of what your primary and off-hand attack bonuses are, see if it says +0 bonus.