It's alot easier to measure the wheel arch height that the overall height... 
I mean, are those figures including roof bars/rails, to the top of the aerial or just with the sunroof open?
The factory numbers can only be used as an approximation as they were produced in a perfect environment using production fresh vehicles. Fourteen plus years of use and abuse will make a significant difference to those numbers.
ok i'll spell it out for the mathematically challenged
measure the overall height - simple - to the top of the roof (or if an estate with roof bars I gave the figure for that too)
deduct from your measurement the factory spec, if the answer is zero your ride height is as it left the factory. if it is negative your ride height is lower, by thta amount. if it is positive your ride height is higher, by that amount.
unless your car has somehow expanded or contracted since it left the factory

i don't know of any better yardstick to use than the height it left the factory at

this is not rocket science even for a troll.