HCG levels help

Leah

I randomly decided to test yesterday even though it was 6 days before my missed period and to my surprise I got a very very faint positive. I went and got a blood test done that same day and my HCG is only at 16. I was told that I would have to retest in a couple days to make sure it’s doubling. Well of course now I’m freaking out and peeing on sticks just to make sure the lines still there. Has anyone had a low HCG in early pregnancy?