Pregnancy

My boyfriend and I had sex yesterday we did use a condom and checked for holes after to be safe (there were none) I am also not on birth control. I did start my period today and yes I am a 100% sure it is my period not spotting. Say if we used a condom and it broke while he came in me and I got my period the next I wouldn’t be pregnant or could I still have the chance? My boyfriend and I have so many questions about stuff like this and we have done some research like looked at planned parenthood and talked to adults about stuff. If someone feels comfortable answering this please do it would be of great help to better our understanding.