Hello, and I hope I can help you today. Pregnancy symptoms vary widely between women, and many of the same symptoms we commonly associate with pregnancy such as nausea, bloating, breast tenderness, headaches and irregular bleeding can also happen from an irregular menstrual cycle as well as pregnancy. Furthermore, modern urine pregnancy tests are extremely accurate and become positive even 10 days after conception, so if your tests are negative, you are not pregnant. So the reason you have these symptoms is that the hormone progesterone, which is produced both during PMS and pregnancy, builds up if you miss your period and causes side effects that can be mistaken for pregnancy symptoms. Women can miss a period for a number or reasons, including weight gain or loss, travel, stress (including the stress of worrying about pregnancy) as well as medical conditions like diabetes and thyroid disease. These conditions can be evaluated by hormone tests which can be performed at a doctor s office, and if it is appropriate, the doctor can prescribe medication which will help you get your period again. I hope i was able to adequately answer your question today and that this information was reassuring. Best wishes, Dr. Brown