Is there any chance of pregnancy?

My wife and I had sex on 24th day(26th June) of her Circle guessing her safe period. Her period is reguler and length is 5days. Her previous cycles are January 4th, February 1st, March 1st, again March 28th, May 1st, June 2nd. I had intercourse in 26th June it was our first time. As far as I remember i didn’t finish because I saw blood in vagine and i stoped doing but still gave her I Pill within 24hours just to ensure no pragnency(I heard pre cum can cause pregnancy) . After 2 days of taking I Pill means in 29th June, my wife got her period 3days earlier than her expected time. The flow was heavier than usual which lasted for 5days. Wasn't it her period?Is it still Possible that she might be pragnent after that Heavy period?