Can you get pregnant right before your period?

Ok so just a last week me and my bf decided to try and have a baby together. The next day after sex my period started. I had no idea it was coming, my periods have always been very weird for example I went almost 7 months without one last year and have skipped one month two years before hand. It has always bounced around so bad, but anyway I want to know if there is a chance or not? I have been told that you can because the sperm can live for up to five days inside and that's about how long min eperiods last from two days to five just depends, this last one lasted for four days. So anyway I just want to know so I can have some peace of mind, right now I'm under so much stress I would doubt if I am pregnant but you never know.