in the world of conception just about anything is possible when you are havinig unprotected sex. if this is truly your normal period it certainly would be less likely to be ovulating a day before. because of your prior pregnancy experience i can understand your concern. you are wise to be cautious. and it is okay to continue to worry a bit until you have a negative pregnancy test or another normal period.
is pregnancy possible if you start a period 19 hours after sex? bearing in mind that the period was about a week early. i had unprotected sex at around 5am on january 1st. around 11pm the same day i started to bleed lightly (light pink). it continued on and off until the third and didn't become heavier. it's been accompanied by some light cramps but nothing i'd really worry about. the last time i was pregnant i also had a very heavy period and was still found to be <negative_smiley>9 weeks pregnant so i'm just being cautious this time.