The problem with your first nub picture is I don't think that is the nub. It doesn't look right to me. To my eyes it looks like a little bit of cord down there. I see a lot of leg which also adds to the doubt I have that I am seeing the nub. I thought I had commented on your original post saying all this, but I guess the monkeys at it.
I looked at your nub shot and had the exact same thought. (I also thought I had posted to this thread before, but I just read through the whole thing and never saw my reply.) Even if that is the nub, it's so busy down there that I would think that could decrease the accuracy of the guesses.
I'm also leaning boy off the new shots. But I'm not 100% sold, and this early you just never know what might happen. This is one of those times when I would love to look back and see that I was wrong.