Why Are My Menses Delayed With Backache And Breasts Feeling Full?

Hi, I came off the pilla couple of months ago and have been having irregular periods ever since. Howevere this month i have not had my period and i think its almost 10 weeks. I took about 4 tests on different days and they all came back negative. I have been having back ache, my boobs have grown but they don't hurt but this could be because i have gained some weight due to no exercise and not eating well. I have pains occationally in my abnomin almost like cramps but nothing. Does this mean anything do you think? COuld i be pregnant?