doesnt sound like your prego to me, just a lighter period..did you not have one in december at all? somtimes our bodies just skip one for whatever reason
It does not sound like you are pregnant. A negative preg test is a pretty good indicator and a period whether heavy or light is a period. If you have regular periods, the fact that you were 2 weeks late may be a sign of an early miscarriage.
if the only time you had sex as nov 28 and that was the last day of your period you are probable not pregnant if you are on the 3 day of your period i would think you ovulated on about dec 25 you whould have needed too have sex on the days leading up to that or that day