Nervous

Hi all, I am so nervous about losing this baby. I have had 3 miscarriages and no successful pregnancies. I am currently 4 weeks and 4 days and I had to get emergency blood work because my hcg was a little low, they did say it may be because it is so early but they are waiting for my progesterone test to come back.. I did take more home test and the line is getting darker but I can’t shake the feeling that this one won’t stick despite doing everything I know I can... I am trying to stay calm because stress is bad but I just need to get past the first trimester. Does anyone know how to not worry? I need this to stay. The last miscarriage was at 5 and 1/2 weeks and the first was at 8 weeks the baby stopped growing at 6.