Scared my HCG is too low...

My husband and I have been ttc for a few months now, and this weekend I developed some issues that took me to the urgent care. Not pregnancy related. But while I was there they did a blood hcg test that came back at 19. They said I was pregnant, but just really early. Based on my calculation I'm thinking implementation happened on about Friday or Saturday. So it's only been 2-3 days. The doctor didn't seem to be concerned about the hcg level, but I'm scared! Has anyone else experienced something like this? I haven't even had a missed periods yet, nor have I even gotten a positive hpt. So I'm worried.