Depo Birth Control Shot/Pregnancy Test..

Theresa • I am 24, been with my husband for almost 8 years been married for over a year! 8/15/14 We can`t wait to have a baby!
I have not had my period for six months because I was on the Depo birth control shot. I know it says it takes 3-6 months to clear from your system but I do not believe that because I know two people who got pregnant not even a month after they discontinued the shot. Since I have not had my period yet does it mean there is a possibility I can get pregnant? It happen to the two people I know. Also, how soon can I take a pregnancy test