misunderstood my doctor still have to wait to find out baby's gender

Ug I was so excited for my appointment tomorrow because I thought I would be finding out the gender of my baby. But I guess I didn't understand and I have to wait for an ultra sound appointment which is at 20 weeks. I just feel really depressed because I thought I would get to see my baby again. I hate this wait I guess I don't understand why they can't use the us machine in their office. :( I feel like crying. So many know the gender already and I just don't want to wait any longer.