Im 20 years old. my periods are irregular my last period started may 24 and ended may 28, i had my first sexual encounter on june 14 was i fertil??

Maybe. Maybe not.: Life is not exact. Ovulation (conception possible) is about 2 weeks before the expected start of one's next period. If worried about pregnancy, can do a home urine test, giving a reliable result 3 weeks after sex (3 weeks after when conception might have been), or 1 week after missing a period. If done sooner, a positive result is likely real, but a negative result may be due to testing too soon.