What Causes A Delayed Period, Fatigue, Appetite Loss, Cramping And Abdomen Bloating?

I have been on the pill for three years but I stopped it this past month after my last regular period that started on March 28th. I have not gotten my next period yet. I have experienced fatigue, a change in appitite there were days were I didn't feel like eating or was not very hungry, and there was time were were I felt a crampy bloating feeling around my lower abdoman. I have taken a couple of test but they came out negative. Could I still be pregnant or is there something else that could be causing it.