Progesterone dropping

So I found out I was pregnant last week after suffering two early miscarriages. I have yet to have any children. I went for blood on Thursday and my progesterone was 23. My repeat blood work this morning showed progesterone of 16. The nurse assured me this is Normal and it’s still above the suggested level. I feel very uneasy now and afraid I’m gonna miscarry again 😩😩😩. It really sucks that I can’t just enjoy my pregnancy. Does anyone know if this is indeed normal and have any similar stories?? I’m so worried.