Why can't my bf get me pregnant

​So we been trying for almost a year but I was. On bc for a few months and plan b befor me n him tried but nothing is working he's cumed in me over and over and over again yet still no symptoms nothing I mean I felt  nauseated a few times on n off my feet were swollen last month but nothing n my bf has some really strong sperm it's like supper white so I don't understand why I can't get pregnant mind u he has had 6 other women pregnant in the past and mind u they smoked and drank and partied all the time, I'm a simple girl I don't do that shit can someone help us I'm even taking a year off school just so I can have my baby