Congratulations on your BFP starz!

As HotI said there is a very wide range of normal in HCG results. They pretty much only use it to confirm pregnancy and to check if levels are going up. It is never used to date a pregnancy. Also, sometimes they report the results as weeks past conception rather than weeks past LMP so that gets confusing too.

If you're sure of your LMP they will just use that to figure out your EDD. As for the scan they may or may not see a heartbeat at 6 weeks, I personally chose to wait til 8 weeks as I knew there should be a heartbeat by then, which would save the stress of if I'd had a scan at 6 weeks and they couldn't tell yet.

Good luck, it's so stressful at the start but hope you have a happy and healthy nine months!