Pregnancy and birth control

So if I’m on birth control (this the second month I’m on birth control Nikki) i can’t get pregnant right? I’ve been taking it everyday and when my significant other and i had sex last week we wore a condom both time. Lately I’ve been very nauseous and very anxious thinking about why I’m nauseous out of no where. Is it something i should be worried about? Should i take a pregnancy test?