So I had the teensiest bit of spotting last week, went to OB for my regular appointment and she said baby sounded fine on the doppler and my cervix looked fine, but she wanted me to come in the following monday morning (that'd be today) for an U/S to double-check that everything looked OK in there.
The ultrastenographer said everything looked totally normal and fine and asked if I wanted to know what I was having.... I said YES and can we check today (I'm only 16 wks 4 days) , and she said she'd try to see.... So, lo and behold, we get down to the baby's crotch area and he/she has their legs GLUED together in a pike-type position!
The U/S lady said she "didn't see a penis" but it was too hard to tell definitively what she was looking at b/c of the baby's position. I moved around, ate a candy, switched sides, etc to try to make the baby move enough to see it's "junk" but it just sat there. The baby was being pretty still in general and sucking it's thumb,  the ultrastenographer said it was probably sleeping!
So I left without knowing what we're having, they will check again at my 20 week u/s (not until mid-october!) but I feel like I will die of impatience before then!!! 
Oh, and OF COURSE, the minute I start driving home from the OB office, the baby starts darting around in there! 

-V

With my last pregnancy, I also had an ultrasound at 16 weeks and the baby didn't cooperate either. It is so hard to want to know and not have the baby spread em! I understand.

Took them til 23 weeks for me and almost didn't see then, good luck to ya