Safe/Unsafe period? Help!

Caroline • Food nerd!!!
I had unprotected sex with boyfriend 3 days after my period, am I safe? Had unprotected sex a week earlier 3 days before my period and used postinor2, period came 2 days earlier, now I'm concerned about how safe I am, cos Glow says im in my fertile period at the moment??? Can I use postinor2 again?