hello, You are mostly suffering from oligomenorrhea (irregular delayed period). Reasons are ovarian cyst or PCOD (most common in your case), hormonal imbalance, stress/anxiety, thyroid problem, weight gain / extreme loss, irregular eating habits, high prolactin level etc. Abdominal pain may be due to pelvic infection or underlying ovarian cyst. In exclusion of pregnancy, you need to undergo some investigations to pin point the diagnosis like USG scan of pelvis, complete hormone assay, thyroid profile, blood sugar & prolactin level, blood DHEAS & testosterone level etc. Consult with your gynecologist for proper guidance and take suggestive measures. Avoid stress/ tension, take healthy diet with Vitamin & iron supplements, control body wt by regular physical exercise and take sound sleep. You need to take hormonal medication to regularize period with other supportive therapy. Be well & take care.