I am so scared!

Went for my confirmation appointment. Doctor didn't tell me how far along I was. There was no heartbeat. Was also told I could be having twins. I have to go back in two weeks. According to my period I should be about 6 weeks. He said everything looked good. So nervous there won't be a heartbeat when I go back. I just want everything to be okay and won't be able to relax for another two weeks!