So I'm exactly three weeks late for my period. I'm 22 years old. I have a 2 year old and stopped nursing in February. Since I had him all my periods have been regular except for the month that I stopped nursing him. I have also been very tired lately. It also seems that I have colostrum in my breasts. All of this seems like I could be pregnant but every pregnancy test has come back negitive. About 4 of them. Do you think that I could still be pregnant, or if not what else could it be.