I had the contraception injection in June and was due the following one in September but did not have it.My period satrted on Sunday does this mean the injection is out of my system and that I can start trying for a nother baby after I've already lost one

You need to speak with your doctor to be sure.

Since you were due in Sept. and did not go... chances are the effects have worn off. Be safe, and check with a professional though.