We had unprotected intercourse on April 19 and she took ipill same day her expected period was on April 26 she got it on April 27 it was a normal three days period for confirmation we did a home pregnancy test after 10 days it was negative  and also did a Ultrasound this month on 19th May but no evidence of pregnancy all are normal .So are there any chances of pregnancy we are tensed as in internet many things are there is there any possibility that it was not period but implantation bleeding .