Pregnant or paranoid...???

My last period was Dec 11th.. I am on the pill.. anyways.. I had a uti and had bn on antibiotics could have been comprimised.. Had on Dec 23rd and we used a condom but the condom broke. I took plan b next day.. around 12 hours after.. I am sick with worry that it won't work.. i took a first response test today and it was neg.. i am currently on my pill free week My period is due on Saturday. Need your advice what do you think>>