I had sex on June 15th he didn't ejaculate in me but I know about precum so I took plan b around 36-50 hours later (can't remember exactly what time) I then received my period almost 2 weeks later and it was my normal heavy flow. I'm waiting for my 2nd period and it's over a week late. Should I be concerned? Btw I haven't had sex since. I've took several pregnancy tests and they all come out neg. just worried that my periods late