Hello, and I hope I can help you today. Your ovaries are not a perfect system, and all women will have an abnormal cycle once and a while. Missing your period can be cause by stress, weight changes, traveling, and other benign causes. When you miss a period and are not pregnant, it usually means that you just didn t ovulate that particular month. When that happens, you basically just have the hormones that give you PMS for a longer period, so you feel bloated, moody and have tender breasts and changes in your discharge. The headaches can be from your hormone levels dropping, which means hopefully you should get your period soon. I would wait another week and if you do not get your period by then, do another pregnancy test just to make sure. You have such PMS symptoms that I m sure it will come eventually... but you may just feel lousy until then. You can obtain a blood pregnancy test at a doctor s office too to make sure, but the over the counter urine pregnancy tests are every accurate if you wait until your missed period to test and use your first morning urine. I hope this information was reassuring and I was able to adequately answer your question, and that my advice was helpful. Best wishes, Dr. Brown