Hey...as you missed your shot in march, you could be pregnant.
Normally it takes a few months for the depot shot to wear of...but im sure its still very possible if you have unprotected sex. If the home pregnany test was negative, then i would assume you are not pregnant. I suggest taking another test in a few days time, if thats still negative, leave it for another few days. Then re-test. If again still negative, you are not pregnant!
If your really concerned you could visit your doctor who could do a blood test to see if your pregnant. Try not to worry... spk to your doctor.
Hmm...the Depo shot (IMHO) is the worst birth control out there. This shot can have symptoms of everything in the book and can last in your system for up to a year. If you are having unprotected sex, then yes you can become pregnant. So my advise if you don't want a baby...use some condoms then. Some women conceive right away after birth control...while others take a few months to a year. So it really depends on how well your body responds to medications.