Fat

I'm starting to begin to doubt the BMI is a real indicator of ideal based on these calculations obtained at my Army Medical:

Height: 168cm [bloody hell i'm a shortie :( ]
Weight: 75kg [blood hell i'm fat.. :(]
BMI [(weight in kg)/ (height in m) ^2) = 26.6

if BMI= 25 is ideal, then (25 x 1.68^2) is the ideal weight which = 70.56kg
Thus to achieve ideal weight, I need to lose ~5kg

Fat impedence test [based on electrical resistance- fat is a good electrical insulator]
Impedence: 400 ohm
Fat mass: 16.8kg
Fat percent: 22.0%
Ideal= 14-20% fat
if Fat %= 20% is maximum tolerable fat, then 16.8/22 x20 which = 15.27kg
Thus to achieve ideal fat % i need to lose 1.53kg of fat

But taking the median of the fat % ie. median of 14 and 20 is 17 and recalculate,
Median fat % range = 12.98kg
Thus to achieve median fat% range, i need to lose 3.82kg of fat.

Argh heck it.. I give up calculating.. losing weight is still so difficult.. losing fat is even more difficult :( Hopefully the Army will whip me into shape..