I had sex 13 days ago and am worried because I am taking birth control medication but during the time I had the sexual intercourse I was also taking an antibiotic, Augmentin, which can affect birth control pills. I used a condom during the sexual act as a means of back up and I am almost positive that nothing went wrong, no breakage or tears. I took an at home pregnancy test yesterday, 12 days after the intercourse, and it came out negative. Is that accurate or should I be worried I am pregnant?