Thanks for your query.First of all let me know your usual cylcle length and whether there is any previous history of similar episode? I also will ask if u hav taken any protective measure either before or after sexual exposure.urine pregnancy tests are usually enough sensitive to detect pregnancy after the first week of missed period and need not to be supplemented by blood hcg.but if ur cycle is irregular there may be misinterpretation for too early testing. Better to visit nearby gynaecologist for detail checkup to rule out other causes.