period while pregnant?

I got my period after days of stressing about it, and it came pretty normal. Mine is heavy for the first few days and lasts about 7-10 days. However, I was online the other day and some women claim that they got their period while they were pregnant. Could all of this just mean that they were spotting and had very light periods so they mistaked it as their period? Or is there a chance I could still be pregnant?