I'm on the shot and had unprotected sex!

hi i'm 21 and at the beginning of this month my boyfriend and I had made the choice get on the Depo shot for more protection against Pregnancy.. well I got the shot on the 3rd of the month...which was after my last period by a week... after I got the shot we had waited a week before we had unprotected sex for the first time.. and since then we've had unprotected sex many times thinking it was ok because I'm on the shot...I'm now a week late for my period, I find myself eating more often and i have a tad bit of a heightend sence of smell.. and i haven't felt too good for the past two days.. I have a fever and feel worn out...and I've been getting headaches more often then normal..and sometimes i get a little queasy, but i haven't thrown up yet... I do urinate quite a bit...and around the time for my period to start I had the cramps like normal but nothing else it went away. and i know that with the shot you can lose your period for up to a year.. but my OB said that usually accurs after a year or so of being on the shot and i've only been on it since the 3rd of September. ..and I have been under a little bit more stress then normal.. I have yet to take a home pregnancy test due to the fact that I don't think it would show up this eairly.. but I would like some of your opinions on what it could be before I actually take a home test today and plan to go to the OB and get the other tests done. If i am pregnant I do plan to keep it theres no doubt about that.

Any Advice about getting pregnant on the shot, if this could just be a bug of some sort, anything at all..