Positive Pregnancy Test, No Baby on Ultrasound: Miscarriage or Healthy Pregnancy?

So for the 2 weeks I've been in miserable stomach pain, my stomach has been cramping up to the point where I'm doubled over in pain crying. I thought it was because I had the stomach flu because I was also nauseous, well my husband told me yesterday to take a pregnancy test since I was late by a week. I took one and it came up positive and I freaked out because of all the pain I had been having so we went to the hospital right away. They ruled out an ectopic pregnancy, and that the pregnancy test was indeed positive.... but they also told me they couldn't find a baby on my ultrasound. They said I have to go back in two days to see if my hcg is rising. The doctor told me he couldn't even tell me if I'm having a baby or having a miscarriage. I'm sitting here unable to sleep or do anything because I'm terrified that I'm having another miscarriage. I just want an answer. I dont wanna be sitting here wondering if anyday I'm just gonna start bleeding, I'm so scared. These next two days are gonna feel like 2 years... :( anyone else go through this and have a healthy baby ??