I see. It’s important to ease your anxiety, but I don’t think that you should rely on easing your anxiety with inaccurate information/assumptions about bleeding.
People can bleed even if they are pregnant so bleeding is not a reliable method to rule out pregnancy. What you can do to ease your anxiety is to learn more about birth control so you CAN understand how diarrhea or vomiting could affect the pill. I’d also recommend using condoms until you understand your pill more and until you trust your pill