I recently started the depo vera shot. I was told that you had to be on your period to receive the first shot. I was on day 2 of my period, and had sex. On day 5, i received the shot. they gave me a pregnancy test, it came out negative, but obviously they are not going to be able to detect a pregnancy 3 days after having sex. i have not gotten my period this month, although i was told that the first month it should come as normal. i have a couple other signs of pregnancy such a frequent urination, nausea, and sleepiness. is it possible to have already been impregnated before receiving the shot?