Periods after sex. I worry about that?

On my 18th day of cycle i had unprotected sex & cummed inside my vagina .took ipill after 2 hour. I had sex before &I didn't bleed that time.But this time I had more tearing pain during sex & I bleed during sex &bleeding continued for few hours.My vaginal opening was covered in cum. I took home pregnancy test 14 days after sex &was -ve. I'm not married & don't want to get pregnant . On 33rd Day i had sharp pain on all over my lower abdomen and was unable to move.periods came on my 34th day of cycle & flow was light with little cramps.On 2nd day of periods  blood has weird smell& color.Also had some kind of lumps like dried mucus( not blood clot)with blood. That  didn't dissolve in water,blood washed away & some small structure of around 1cm length & almost transparent was found.Is it my baby or something Or miscarriage?should i worry about that? Now I'm on my 3rd day still blood has smell.now color is light red & flow is light. No thyroid issues . periods is irregular