What Causes Vaginal Bleeding After Taking I-pill?

respected doctor i made a intercourse with my partner. i gave her i-pill . I am 28 and she is also 28. we made intercourse on 12th may after just her period finished on 10 may. after taking the i-pill her period came again on 15th may. then long gap her periods came on 25 th june. now till date her periods are off. Please suggest me.