Delayed Periods With Bloating, Gas And Increased Thirst

I have a very regular 28 day cycle and was due my period yesterday and havent had them yet. I did a test this morning that was negative but for the past two wks + i have had feeling like bloating, gas hars to sleep with period like pains and am more thirstier than usual. Today though i have a stabbing like pain at my hip- pelvic area that travels to my groin area and at times into my thigh.....could i be pregnant and have a problem or what else could cause these symptoms and a missed period???? please help:(