ya that sounds more like implantation bleeding rather than a period and would have been around the time implantation bleeding would have occurred. If it was lighter than a regular period then it was implantation.
I don't quite follow bgarcia's comment. Yes, sperm can live for 5 days, but it has to be during your fertile time to get pregnant. Are you sure that was a regular period and not implantation bleeding? Some people also have some bleeding when it's time for their period even though they are pregnant. If you go for a sonogram when you think you're 7-8 weeks, they can give you a fairly accurate date.
Congrats on your pregnancy. The reason you got your period Feb 5-9 is because the sperm lives in you for about a week if I'm correct. So in between that time is when you got pregnant. I hope I answered your question