Positive hpt then negative hpt still no AF

Hey ladies! AF was suppose to show on 11/19. She never did so I tested that day and probably everyday since then. Thursday and Friday were both faint positive and pregnant 1-2 weeks on CB digital w weeks estimator. Saturday I took a test in the morning and it said not pregnant. So I took a cheap one that afternoon and there was still a very faint positive. By Sunday another test was negative and each test since then has been negative. I'm aware this very well could be a chemical pregnancy....if so when will AF show and more importantly should I worry that AF hasn't showed and my tests are showing negative?