Confusing HCG Levels

Hey lovely ladies, so I am 7 weeks and 2 days and I went in for a scan at 6 weeks and they weren’t able to see a heartbeat so my doc sent me to get my levels checked to see if that matched up with the scan results and my first HCG result came back at 40,000 and then 48hours later I had another and those results came back at 44,000 and then she was concerned so sent me for another blood test just over 48hours after that one and it came back at 46,000 I know your levels are supposed to double so I can’t help but freak out. I’m going in for a scan on Monday to see what’s happening - has this happened to anyone else with a positive outcome? We had been trying for over a year and are so excited to finally be pregnant and I just need some clarity?!