My cycle is always 28 days and my period is like clockwork always on the same Sunday of every month and 4 days long. This month my period was due on the 7th and didn't come till the 9th, only lasted 3 days and wasn't as heavy as usual. I took one test on 7th or 8th and one two days later and they were both negative. I've have been peeing constantly and my headaches have become worse. I was sick to my stomach earlier today and feel like I'm always sleepy and always hungry. Im not sure if I'm coming down with something or what? Please help!