Hello, Pregnancy is possible only if you were involved in unprotected sex around ovulation time or fertile period. Here, you need to undergo one blood test for beta HCG to confirm pregnancy. In exclusion of pregnancy, other reasons for late period are hormonal imbalance, ovarian cyst, high prolactin level, stress/ anxiety, thyroid problem, wt gain/extreme loss, irregular eating habits, psychological factor etc. You may require some investigations to rule out underlying pathology through USG pelvis scan, thyroid profile & other hormone assay, blood sugar & prolactin level etc. Consult with your gynecologist and take suggestive measures. Avoid stress / anxiety, take healthy diet with vitamin & iron supplements, eat more fruits & vegetables , drink plenty water or juice and maintain genital hygiene properly. Sore breast is due to progesterone hormone. For breast discomfort, you can wear tight breast support & take prime rose cap. If you need further consultation with me, then you can visit http://www.healthcaremagic.com/doctors/dr-soumen-patra/63326. Take care yourself.