Hi ya,
I can't see a nub either, sorry.
I think unless you are asking what the gender is you probably won't see much at the 20 week scan, i know i didn't, the side profile can easily hide any boy parts, or lack off, with the leg etc. Good luck though, hope you catch a glimpse of something, i am in exactly the same boat, husband doesn't wanna know so we are team yellow and its driving me crazy. xx