Irregular periods (2 month avg.). intercourse on jun 9th. today is 26 days after it. no symptoms. all urine tests negative till today. chance?

Pregnancy unlikely: A urine pregnancy test, done correctly, gives a reliable result 3 weeks after sex (3 wks after when conception might have occurred). If done sooner, a positive result is likely real, but a negative result may be due to testing too soon, and lead to a repeat test. If a woman gets her typical period, then she is most likely not pregnant. If periods vary a lot, she can test occasionally when worried.