Hcg concerns


On 3/4 my nurse advise I go to Er due to cramping and bleeding and to rule out an ectopic pregnancy. At the ER the doctor ordered a HCG test and an ultrasound. Hcg came back as 22,004 and ultrasound showed fetal pole and yolk sac where it needed to be. Tech could see cardiac activity but was unable to measure it. I was measuring 5 weeks and 5 days which was right on track. 9 days later I had a follow up appointment with my ob and did another blood draw for HCG and results came back as 47049 (7weeks). So in 9 days my hcg only doubled. I’m very concerned that this will end in a miscarriage. Am I over reacting? Tomorrow is my appointment for a follow up ultrasound and I’m so scared.