Can i be pregnant if we had sex on the 37 days cycle? i have an irregular period.

Hard to guess: With irregular periods, even harder to guess. A urine pregnancy test gives a reliable result 3 weeks after sex (3 weeks 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 thus lead to a repeat test. If a woman gets her normal typical period, then she is not pregnant, and a test is not needed.