hCG levels

According to my last period, I am 4 weeks and 3 days pregnant. My hCG was 1400 as of around 1:00 am 02/01/15. I was in the ER for an unrelated symptom and they did an ultrasound and couldn't see the gestational sac. The doctor said this is most likely because it's so early in the pregnancy but could also be from an ectopic/tubal pregnancy. I'm going back tomorrow morning 02/04/15 to have my levels checked again and have a sonogram and I'm so worried I'll get bad news. Advice?