Period and pregnancy

me and my husband had sex in September I got my period in October about 2-3 weeks after we had sex in September. We had sex in October after the period, missed my November period and found out I am pregnant. People are saying it’s possible to get a period while pregnant because it’s happened to them or been implantation bleeding, however my doctor told me that there’s no way and implantation wouldn’t have happened like that. She also is marking my November as my last and said the measurements are adding up to that. So I’m going to go with we conceived in October? The issue is I was ovulating both times, but doctor said I’m measuring near a October conception is this accurate?