dunno if this has been pointed out before.
know someone who has one extra digit on their right hand, but only the normal five on their left. The same with his mother, grandfather, etc. back through his family history. So his body is not symmetrical.
so from your earlier argument, your friend could not have been intelligently designed.
These sorts of mutations that cause asymmetry are quite common, so why haven't many such asymmetries propagated throughout the history of evolution?
answer: THEY ARE.
take a picture of yourself looking STRAIGHT into a camera. cut the photo in half in some photoshop-like program, and make two pictures. one of only right sides, and one of only left. compare.
human beings are not symmetrical.
if you want to go farther, take an anatomy class. we have three lobes on one lung, two on the other. our heart is offset to one side. in fact, MOST of our internal organs are assymetric, including the brain.
studies have also shown that people rate perfectly symmetrical images of people (photoshopped as above) as more attractive than asymmetric ones. therefor, symmetry is a property selected for, via natural selection.