I posted on Tuesday that I had an ultrasound and my doctor thought baby only had one kidney, so I had to go see a high risk specialist today. It was good news, he has a second kidney, it is just not in the normal spot but down lower (it's called a pelvic kidney, I guess). It was smaller than the other kidney, but the doctor thought it seemed to be functioning normally, and aside from a slightly higher risk of infection and reflex shouldn't cause any problems. I have a follow up in three weeks, but he seemed confident it would be fine. Thanks everyone for your well wishes and anecdotes!