Rainbow baby- low HCG levels

We are expecting our rainbow baby.. but I am having a very hard time relaxing and being happy. I am terrified this pregnancy will end just like the last one. I have tried being as positive as possible but my HCG levels are low. I had my first blood draw 24 hours after I got my first faint line and it was 11, two days later it was only 19 (72.7 % increase). So it didn’t quite double. This time my progesterone is pretty good and I am on progesterone supplements to be on the safe side. Anyone else have low HCG in the beginning and everything turn out ok??