Maybe I'm confused but it looks like that tape starts at 4cm. That would make your arm 14.3". Sounds much more accurate since mine ar 15" and I weigh 30 lbs more than you at 6' 4".
I find it helps to leave your hand open and let the bar just sit on your fingers rather than making a tight fist around the bar. Other than that there are wrist straps.
try not to listen to the people hear without first doing some reasearch, articles like this are insightful:
http://www.medicinenet.com/script/main/art.asp?articlekey=50900