so i am sexually active, i’m 18 years old, and have a long term boyfriend, my period is normally a couple days early or late but this month it is 13 days late, so when i missed it by a few days i took a pregnancy tests and came back negative, then a week after it was due i took another and it was still negative, does anyone know why my period is this late and what else should i do? me and my boyfriend are refusing to have sex as we’re both so worried, please help me