how long am i gonna wait to be pregnant?

Mary

My depot shot supposed to be on May 3rd 2014,but I didn't get a shot because we decided to stop it and we want a baby I had period June 3 2014,but it was really light I had it for 2-3 days. but we always had sex after that my period.. and now this July I don't have my period yet but I tried the pregnancy test and result was NEGATIVE. how am I going to do to get pregnant...??

please anyone...