Scared of having a miscarriage!

Went to the emergency room today due to cramps and a feeling of pressure down below. According to my LMP I should be 5 weeks 3 days. My hcg levels were in the 2,000's but they could barely see my gestational sac. They said I could have miscalculated my conception and I am earlier in my pregnancy than I thought (which I am praying) or I will miscarry. This is my rainbow baby. I can't handle losing another. Please say a little prayer for me that my levels continue to go up and our baby will be ok! I am so terrified! If anyone had something similar and ended up having a healthy pregnancy please give me hope and share your story!