can someone tell me what's going on..

went to the dr yesterday and for our my hcg levels are a little over 20000, they did an ultra sound and said they could only see the gestational sac ahd yolk sac. I'm not sure how far along I am.. I had a miscarriage on April 29th rhis year and never had a period. I'm a little scared and worried. has this ever happened to anyone and then later on saw the baby?

this was the first test I took on the 3rd ov rhis month

this was yesterday.

I wish I knew how far along I was and everything. I'm just scared of having another miscarriage