I got a depo vera shot in march and was suppose to get my 2nd one in June but I skipped it. The whole time i was on the shot I continued having a period and I had a period June 6th. Well the beginning of July I started getting cramps and a headache so I was expecting my period which never showed up. It has been over 2 weeks now with no period and I am now experiencing nausea, fatigue, headaches, acne, and on and off cramps but negative HPT. Could I still be pregnant and if so why is the test negative?