Possible MMC? Worried

Hi everyone! At 5w6d I had some bleeding that started brown, turned red, then passed one small clot, and dried up and went away. I just knew I had miscarried. I went to the doctor the next day and had an ultrasound showing a gestational sac and yolk sac measuring right at 6 weeks, no baby seen yet. The US tech said it looked perfect and firmly implanted with no blood surrounding it. She said we were probably just a day or two off from seeing a baby. My HCG doubled appropriately and I am on progesterone supplements. My next ultrasound is tomorrow. I am just so nervous that there still won’t be a baby as I saw my son at 5w5d and had no bleeding with him. Especially not clots. I’m afraid the progesterone stopped the miscarriage but the baby won’t grow. Does anyone have any insight? I saw my son at 5w5d in my last pregnancy.