abnormal Gestational sac

Jmbk
I went to the doctors (Friday) today because I was having pain from a UTI. I should be 4 weeks and 5 days pregnant from my lmp. Tuesday and Thursday of this week I got an hcg count, on Tuesday my count was 356 on Thursday my count was 1000, and my progesterone levels were good. Today (Friday) I had a sonogram due to some slight pain in my lower back and the tech said that my gestational sac was slightly abnormal and measuring at 6 weeks. Google is completely freaking me out, has any one experienced this? I have to call my doctor in the morning and possibly get more scans within the next week.