You were protected if you were on birth control. Maybe I’m not understanding.
Did you start the pills on a Sunday? Or, how did you start your pills that you are concerned about this month? Besides the nausea.
Edit: the urine pregnancy test might work if you’re pregnant, but it’s really likely you get a false negative even if you are pregnant, because the pregnancy would be too new. Your HCG is likely below 20 still if you are pregnant.
Maybe call your doctor tomorrow and ask what to do. I think mostly likely you can stop if you are concerned and then start the pills again in a month. I’d ask the doctor.
I never waited when I started the pill. I assumed I was protected from day one.