Bleeding while pregnant?

Has anyone had what they thought was their period, only to later find out they were pregnant? I was due to start my period on the 9th of this month, however I started bleeding lightly on the 3rd, exactly a week early and at 10 dpo. It was a very light flow for 2 days, and i started spotting yesterday then it stopped completely. I have had continued breast soreness the entire time which isn't as much of a big deal but I have also had nausea off and onthe past few days, it seems to get worse by the day. What do you all think? I don't go to the doctor until the 18th