I had my menstruation the week before last week. I thought it has stopped so we had sex with my boyfriend but the next morning, I saw blood on my underwear and that was the last day of my menstruation because after that, there was no blood anymore. However, one week later, I am bleeding again. And I am worried that I might be pregnant because we had sex again the day after that day that my menstruation ended and we didn't use any contraceptive. Please advise