Nervous

I had my first US today and they had to do it transvaginally because nothing showed up through my uterus. They could only see a very small gestational sac but no yolk or baby, stated it seemed like I was only about 4 weeks and 6 days along but was supposed to be 6 weeks 4 days. I had my levels checked last Friday they were 474 and yesterday jumped to 1,739. They think I must have ovulated late since I did not get a positive test until last Tuesday July 14th. I am still nervous as I had a mc April 4th at about 4 weeks. Anyone have similar? Need positive thoughts please!!