I had the depo shot done a few weeks ago and the nurse said it would take 7 days to work. However i had unprotected sex within these first 7 days,and since ive experienced pregnancy symptoms,is it possible im pregnant? As i know the depo basically tricks your body into thinking its pregnant,ive done 3 tests,one 2 days later that said negative and the other 2 i did a week later but they both said invalid,even though i followed all the instructions? Please help,quite confused atm lol thank you.