Lower HCG

Did anyone have lower HCG to start out and it be okay? Mine was 46 at 4 weeks pregnant. It has doubled like it was supposed to and I am now 6 weeks pregnant (first ultrasound next week) but I am just terrified about not seeing a heartbeat. I have had 3 miscarriages this year and my HCG has always started out pretty low. This is the highest it’s been but I’m still terrified. Has anyone started out this low and it been okay? I’m praying this is our miracle rainbow baby. I have just read that low HCG can indicate something is wrong.