BF% is not just about ab definition, you have no deltoid striations, and may show slight nipple puffiness... No less than 10% might be as high as 12%..!!
Not 20, Not 18, Not 16, Not 14... well 14 is plausible. 12 is somewhat plausible. 12-14%
I just got dxa scan at 20, so I think I'm better able to judge body fat now. I want to get one at 8-10 and really have a benchmark.