Peckish, the reason I put "Natural Waist" is this gives you an idea where to measure. The natural waist is the smallest area between your breast and your hips. If you use this as a starting point and then adjust your pattern from there, chances are you will get a good fit.
I am very short waisted and yes I agree that it's almost impossible for me to buy a pair of pants that fit. Most pants that fit my butt usually come up over my ribs. SO I quit buying clothes and make my own. Even shirts are a pain since they hang to long, not what a short person needs. It use to be funny when I was tiny because I could buy a shirt one size larger and then slap on a belt and have me a dress.