Aircraft Balanced Condition
What is the condition of the ball in a hover? If the aircraft is loaded with an off center lateral CG, the ball will be off center in a hover. The string is NA at this point in flight. Now in forward flight, (cruise) put the ball in the same position as observed in the hover and you should be pretty close to trim. Now see what the string indicates in comparison to the ball position? Must agree with earlier post, if you are loosing sleep on this, you are pretty fortunate with no other higher priority matters at hand.