A bit late to post but saw it now.

My son has had a circum too and his is nowhere to be seen either. It is as you say it "sucked in". The dr. who did the circum said that he does have pee-pee it's just embedded in amongst the puppy fat. He is quite a solid boy. When we wash it, and push the puppy fat back his pee-pee magically appears. The dr assured us that as he gets older and loses the puppy fat it should be normal.

Nothing to be alarmed about. But i know it does look weird!