last had my periods on 30th April,haven't got my periods till now.had unprotected sex with my fiancee say 3 times in May.the 1st one on 10th,then 20th and then 31st all in May.had a urine test but it showed negative.am ready for any results now but is there a chance that i could be pregnant?we always use withdrawal method and he has never gone wrong at any time.i have funny cramps lately yet on checking myself i never find any b blood stains,then nusea,headache at times.........please advice