the irregularities in the menstruation
of your girl friend are most probably due to i pill
1.as she had her periods in 16th and intercourse was on 22nd, which will be 6th day of the cycle, the chances of ovulation on that day is low, so the pregnancy
chances are also low, but cannot be fully ruled out.
there is 8% chance to become pregnant with single act of intercourse.
2.urine pregnancy kits are available on-counter in medical shops.
3.you better visit local gynecologist, she will guide you.