Hi pastelplants,
It sounds like you're having a lot of anxiety around pregnancy and also that using condoms and/or withdrawal as your primary methods of birth control are not working well for you.
You can take a pregnancy test 14 days after the risk and/or after your period is late. With a negative test, you can repeat in one week to confirm. Periods can be late for all sorts of reasons, pregnancy and otherwise included:
M.I.A or, Dude, Where's My Period?
I also encourage you to check this out:
Birth Control Bingo! and see if you're interested in any other methods of birth control, as well as note the effectiveness rates of each and come back with any questions you might have.