Hello, First of all, you should undergo one blood test for beta HCG along with USG lower abdomen to confirm/ exclude intrauterine pregnancy. In exclusion of pregnancy, other reasons of delayed period are ovarian cyst (most common), psychological factor, hormonal imbalance, stress/ anxiety, thyroid problem, wt gain/extreme loss, irregular eating habits etc. Do some investigations to rule out underlying pathology like Thyroid profile & other hormone assay, blood sugar & prolactin level etc. So consult with your gynecologist at the earliest and take suggestive measures. Avoid stress/ anxiety by regular deep breathing or yoga, take healthy diet with iron supplements, control body wt and maintain genital hygiene properly. Sore breast is due to progesterone hormone. Wear tight breast support & take prime rose capsule to get some relief. If you need further consultation with me, then you can visit http://www.healthcaremagic.com/doctors/dr-soumen-patra/63326. Take care yourself.