antibiotics and the pill

So I had a little unsafe stupid moment with my boyfriend that lasted all of 2 minutes because I realized i’m on antibiotics for tonsillitis and a steroid for it too and I know some antibiotics are know to counteract the effects of my birth control pill I take so we quickly stopped but my bf says there is always pre cum, i’m very panicked and don’t know if I should buy a plan b? I recently took one a week ago for another unsafe moment but I just don’t know what to do i’m panicking please help