help 😩

So i have the birthcontrol implant in my arm and my periods usually last about 3-4 days i had sex the day i was off only reason im concerned is because a girl i know has the same implant and just found out she was pregnant. He came in me 2x .. not sure if im suppose to be very fertile since i had just been off one day. I've never let anyone cum in me before but it definitely did not seep out either time he came. should i be worried?