I learned in Bio that you can get pregnant before, during, and after your period because the sperm stays in there for a few days. Normally it’s only a few but generally before your period is when you start ovulating and sperm can stay in there for up to 5 days sometimes if you’re ovulating so generally 7 days before you run a better risk of becoming pregnant because of that. But basically, no matter when, if you have sex without a condom and he ejaculates in (or on sometimes) your "area" then you could become pregnant. I think a lot of people forget these things sometimes, I just hope any of this helps.
good luck!
Kayla