Why not buy a dollar store pregnancy test and just use it tomorrow morning so you can know for sure? Then you won't have to stress out waiting for your next period to come.
Ahhh. If a condom was used pregnancy would be unlikely unless you had a form of failure. I don't think you really have much to worry about. It sounds like it's just your body working to get back on track from the shot.
NO I'm not trying to get pregnant, and a condom was used. I was suppose to get my last shot on November 1st. My family and the doctor decided to take me off because it began to break my face out really bad. The doctor specifically told me that It'd be a good chance for me to get pregnant then. But, I didn't listen. I might go ahead and wait till after Jan. to see if my period come. If not then I'll do a home test.
The first place to start would be by taking a pregnancy test. If your last shot was in August you were due back sometime in November. (I think. Might be October you were supposed to go back) Because it can take months to get out of your system it can also mess with your period as your body adjusts to not having hormones in it. This can also cause you to feel sick. Unless you're trying to get pregnant, (which I hope you're not) you need to be on birth control and always use condoms.