As you say, you had sex on 5th may &got period the same day. I don't see any chance of coception (provided you did not have sex following your periods in May . If not__ Please don't worry.) you will get it in couple of days. you can repeat the pregnancy
test after a week. Sometimes tension also cause the delay
if it turns out to be -ve even after a week, take Tab. Regestrone
1 tab two times a day for 3 days . within 8 days of taking, you will have bleeding.