Period & Pregnancy?

I’ve heard some women have their periods throughout pregnancy but I only personally know one women who does. I’m not sure how accurate it is otherwise or if it’s a disease? I haven’t researched much and some women will explain that it can happen and others are plain out rude and say you’re stupid if you think that. Anyways, I’m concerned. I got a positive test, then my period came heavier than ever but without any cramping (I usually have bad cramps) and my boobs hurt rather than my nipples. My heart rate was extremely elevated and I felt like I was going to pass out, so I expected miscarriage? Then, today, two days since my period ended, I took a test and got a positive? I’m so confused .