4 days ago I have unprotected sex. I was on my period. Maybe 3 or 4 days into it. I'm terrified that the shot didn't work and I'm pregnant. I've had the shot 3 times but idk if my period may have stopped it from working. I'm way to young to have a child. I'm a senior in high school. The guy I did it with says he's 99.9% non fertile but I believe he's lying to me... I can't have a kid I really need answers guys. Please help..