Stressed for no reason ?

I had sex on December 31st, we used a condom and I had been on birth control for a month and took them regularly, My period came January 3rd and lasted 5 days. I am on cycle day 30 and my period hasn’t came yet.

1 question

1) If I would’ve gotten/gotten pregnant from the time I had sex on the 31st, wouldn’t I have missed my period on the 3rd or was it to early to miss a period.

If anyone else was asking this question I’d tell them not to worry because they used condom and pills. But my cycle usually doesn’t last 30 days.

Thank you for any advice or comments.