could use some encouragement right now

Hi ladies! I just left the er, on going cramps lead me there. Even though they didn't say anything was wrong I'm just wiggling out. I'm 5 weeks 5 days pregnant with baby #2, and the ultrasound tech told me my hcg level was 640. Which was the first thing that got to me. Second was the fact that the dr told me that he didn't see anything on the ultrasound, even though it may just be too early I panicked. I had surgery back in Feb to remove a cyst that I had in my right ovary and it's back. I'm just one big ball of mess right now. I'm afraid but I'm hopeful that at my follow up appt everything will be just fine. My blood work was perfect. I just don't know how to calm down and chill out right now....is my level normal? Not seeing anything on the ultrasound at 5/5 is that normal? Please somebody help me