Question: Confused

I had recently been on depo. I missed my last shot in October and was pregnant by December. After that I got back on the shot. I missed my shot in June, had my last period on july 8th and my expected period (aug 6th) is late. I took a positive pregnancy test on the 5th and a negative pregnancy test on the 6th. Should I take another test or just accept that I am not pregnant? My period is 3 days late as of today. I have been tired, nauseous, sore boobs, and cramps. I am just really confused!!!