Ob-Gyn questions? Ask a gynecologist online.
With irregular periods, it is very difficult to say when a woman ovulates. Most women ovulate about 14-16 days after the menstrual period, but in a woman with with irregular periods, it can occur at any time in the cycle.
Sperm can stay active in the reproductive system for up to 48 - 72 hours after sex.
Since you had sex within 48 hours with 2 men, it will be very difficult to comment on which man is the father.