your thinking process was great until the macro lens :) and that is why you probably did not go with more (or less, i never know is more less or less more) F stop. 

it was a 35mm macro lens, and the flower was small (really small) so to try to get it all into the shot i went for f/14. and because flower was not running away and i had no light stand for UV i just placed camera on the flor and go with 2 seconds (one before or after was probably up or down shutter speed), and ISO was 200 just be low and not to long on shutter speed.