Wish I could help, but I'm not familiar with Barnvelders. Appears to have a well developed comb, wattles for that age tho. Could be an early developing pullet, but my guess is a roo.
FYI, in case you didn't try, the first ICON in the image section is for 'insert image'. If you utilize that, it will bring up a box that allows you to search your computer for the image you want to insert. I understand that some people have trouble using this from their phones, but my experience is only with inserting images from my PC and it works well in that situation.
With barnies they are pretty easy to sex at this age. Can you get a picture of the chest? The comb and wattle are pretty good indicators, I have 20 week old barnie girls and none have anything near that big or red. However, the chest can tell a lot, girls have lacing, boys generally have solid black breast.