I have been having signs of pregnancy but i have taken 15 pregnancy test and they all have came back negative, i've been off the depot shot for 4 mont?

See your doctor: Then you need to see your doctor, to see if there is something else causing your symptoms that may need to be treated. Urine pregnancy tests aren't 100% accurate, but if you've had that many come back negative, it's unlikely your pregnant. I advise not to spend any more money on these tests and to go see your primary physician. Feel better.