Worried only saw gestational sac at 5wks.

The dr said its still early. According to my LMP I'm suppose to be 6wks. My gestational sac measured at 5wks n a few days. I'm just so worried cause no baby was seen. My hcg at 4wks was 2500. I just feel so scared. I go back in a couple weeks I'm praying a baby is seen whrn I go. Prayers please