I would just add that unprotected sex exposes you to all sorts of infections and some infections cause infertility. ie Chlamydia. So get tested, even if you know your bf is faithful etc. He could have it from a previous partner.

If you dont want kids yet you could always get a contraceptive anyway.

The window of fertility is about 6 days and high level of fertility is on just a few days.
If you are curious about your fertility this is the expected time frame that Drs will consider testing but usually they test people who have the intention of becoming pregnant.