What Causes A Delayed Period, Headaches, Bloating, Fatigue, Cramping And Flatulence?

Hi the past 2 weeks I've been getting headaches on and off everyday, have been bloated, had mood swings, and extremely fatigued. The past week I've been slightly cramping, very thirsty all the time and gassy. We have been trying to conceive so I stopped taking my birth control this month and haven't been using any protection and I'm now 2 days late for my period. I always get really bad cramps the week before my period but last week it was only slight cramps. I've taken 4 pregnancy tests now and all came back negative.