What Causes Delayed Period And Fatigue?

I been late on my period for about 3 months now, and i have taken numerous pregnancy test and they all come back negative. I have been extremely tired and have not been feeling well at all. I tend to get pain in my back and lower abdomin every once in a while, kind of like mentrual cramps. I havent had any bleeding at all so could i still be pregnant even tho i keep getting negative results?



any help would be appreciated