What Causes Delays In Menstruation?

I got a lupron depot shot on Friday of last week. I was suppose to start my period on Monday or Tuesday of this week. I have not started. Will I have a period since I received the injection ? Also, I took 2 home pregnancy tests that were both positive. The doctor gave me two tests today as well that both tested positive. He said that they are false positives. I don t understand how you can just say they are false positives without doing blood work.