Anyone can answer this for me?

Alright here is my question. I just got on the pill. Finishing up my third week on my first ever pack. When given the pills I was told to wait until after the first week till I could have sex without a condom. I had every intention on doing that however I got caught up in the moment and on the 5th day had sex without a condom. Could I be at risk for pregnancy or no. If so I'm about a week away from my placebo pills aka inactive pills(to get my period) should I wait and see if I get my period on with my placebo pills or go get a pregnancy test. And how do you test while on the pill. Doesn't the pill mess with all your hormones. I just don't fully understand that part of it. And I always take my pill everyday at the same time never missed one. And if I only get my period once a year how should I be checking and how often, that the pill is doing its job.(get a pregnancy test every once in a while) please help if you can.... Thank you:)