My period regularly, without fail comes on the 15th day of every month and lasts 3-4 days EVERYTIME, but I am 2 days late. I took a test yesterday and it was negative. I am 16. I last had unprotected sex on the 6th which should have been when my ovalation passed and even of my period lasted a week there's just no way I would have still been ovalating when I had unprotected sex. I've been stressed lately because of exams. I've been getting my usual pre-period pains the entire week but, giving all this, am I pregnant?