First Apt

So I had my information apt today to confirm I'm pregnant.  I got 5 BFPs since 4 days before my period was due.  Dr thinks I'm  4 weeks 3 days they suspect.  Did a physical exam all was good gave me a ton of information.  Then the doctor tells me to schedule my first real ob apt for 3 weeks for sono and physical exam and at that point they can pinpoint exact dates and if pregnancy is viable.  Why did he have to say viable?!  Everything was exciting and happy until he said that.  He couldn't just say to see that everything is ok.  Uugghh now I'm going to be a nervous wreck for 3 weeks ?.