Wasn't I supposed to relax now?

I told myself that once I got that 16 wk u/s behind me that I would relax. Sadly, it's just not that easy. I have had some relief, but it's not like I can just let go and wait to get to 40 wks. The thing that I can't get out of my head is my local RE saying to me last year, "that uterus is never going to support a pregnancy!" It haunts me. I'm so afraid that she may be right. Every day of this pregnancy I have been amazed that nothing has gone wrong. I hate that I feel like I'm spending the pregnancy waiting for something bad to happen. I'm trying so hard to enjoy it. What's a girl to do?