Hello dear. Understand your concerns. you are secured from pregnancy because you have sex in safe period, there is no chance of being a pregnant. During safe period, ovum is not released so no fertilization has been occur. But if you had sexula intercourse in unsafe period earlier with out ejaculation, then pregnancy is possible. As precum before ejaculation contain sufficient sperm and it enter into vagina unknowningly, so cause pregnancy. Gastrointestinal problem dose not cause delay in period. Your period could be dealyed by the hormonal imbalance, excessive stress, change in life style and dietary habit, ovarian cyst. Reproductive hormone analysis, USG scan, ovarian follicle study will help in the diagnosis Period can be induced by the progesteone pill under the advise of the hynecologist. I hope this will help you. Thanks Dr.sagar