Me And My Boyfriend Had Unprotected Sex Tuesday Night I

Me and my boyfriend had unprotected sex Tuesday night I got off my period Tuesday Morning .Wednesday I woke up to spotting and cramping. I woke up this morning not spotting nor bleeding I am on birth control but have not taken them in a week because I thought I was pregnant so I stopped because I heard it will kill the baby if I was pregnant. what could the spotting and cramping one day mean? Could I be pregnant