Chemical? MC?

Hey everyone on January 26 I got an obvious positive. Two days later I took another test and you can barely see a line. It’s been about 6 days since the second test and I have yet to bleed.

When I got the positive I took a lot of tests to make sure it wasn’t a false positive; they all came back positive. When I got the negative I also made sure to take plenty of tests to make sure it wasn’t a false negative. Now all my tests are showing negative but I’m not bleeding. I got the positive around 4 weeks from LMP. So I’m guessing it was a chemical? But where’s the blood? I know HCG is commonly produced when you’re pregnant but could anything else trigger HCG? Honestly I don’t even know anymore. I’m not on any drugs or anything.