Could I still be pregnant??

So my period was suppose to come 8/10 but it was three days later and it didn't come I get regular periods every month so i took a test 8/12 and it was - then I started spotting the next morning (8/13) my flow became regular later that day and it went off today 8/15 which means it only came for three days I usually get four day periods the whole time I was very nauseous and sick to my stomach had this ever happened to anyone? Can I still be pregnant?