I have been on the shot since may of 2006. In Nov. I decided it wasn't for me and did not go back to get my shot. My period in Dec. was two weeks late. Then, a week after I went off I spotted for one day. My period did not come at all in January. Every test I have taken has been negative. Is the shot having some kind of effect on me since I went off three months ago, or am I pregnant and not far enough to tell? Please shed some insight on me so I won't make an unneccessary trip to the doctor.