I'm stumped!m or f?

Hi ladies I'm new to this board but am not sure how to upload a photo from my phone. My 12 week u/s shows a distinct nub.it is fairly flat and has a kind of knob at the end and is a bit forked. It is on an angle but looks to be resting down. I'm Probably wasting ur time without showing the photo so sorry about this. I'm having twins and the other I will die of shock if it isn't a boy. If any of you are on Facebook I put a photo ob the nub theory page-it's about the 2nd or 3rd one down-my name is Katie. I have a 3 year old son and would love a daughter. If any of you do make the effort to go Chec k it out I would be so appreciative.

 i cant find the page on facebook and can you post a link to the page its on and ill have a look for you