Whats the chance of getting pregnant

So I knew what I was doing and I was hoping my man would be careful. Im 5 weeks postpartum and me and my man had sex, well he cummed on my vagina literally right on the opening🤦🏻‍♀️. And before sex I literally told him not to. Well anyways, now I am paranoid that I could be pregnant again, what are the chances of getting pregnant if he pulls out but cums on the vaginal opening?