Spade22 is right it could be either or.... I know when I first came off the depo shot my cycles were ALL MESSED up and it took almost 6 months for them to regulate.... Just wait a week and take a test and if you still feel preggo after that, visit the doc! Good Luck
Wait another week and retest. If you still dont have any answers, visit your doctor who can do a formal workup. Its possible you are pregnant, its also possible your body is taking awhile to regulate after coming off the birth control.