Hello,
Pregnancy is possible only, if unprotected sexual intercourse is done with ejaculation around ovulation time in regular period. Ovulation occurs approx 14 days before due date. Though using condom has 15% failure rate whether in pull out method 15-28%.
Therefore, you need to rule out pregnancy by doing one
blood test for beta-HCG at the earliest. Early pregnancy test may give negative result.
Other reasons for delayed period are
hormonal imbalance (most common in this context), stress/ anxiety/ mental upset, irregular diet pattern, wt change,
thyroid disorder etc.
Consult with your gynecologist for relevant examination & investigation like USG pelvis, complete hormone profile etc
Avoid stress by regular deep breathing, take healthy diet with
iron supplements, keep bowel habit regular, maintain personal hygiene and take proper sleep.
Be well & take care.