He hasn't pooped in 11 days

My son is 14 days old and he pooped at the hospital the first night and the next day. I brought him home and he hasn't pooped yet. I talked to the nurse frequently and she advised me to take him to the local hospital because it was a saturday. They examined him and found nothing to be wrong and than called a pediatrician who said he's absorbing everything. He had another appointment and found out at 9 days old he was one pound less than at birth... now I'm feeding every hour every two at night and he still hasn't pooped!!! I can't help but be worried and he has another appointment tomorrow but it's so hard thinking about this all day does anyone have any experience similar to help?