Maybe pregnancy

About 2 maybe 3 weeks ago my boyfriend an I had sex multiple time with out a condom I'm on birth control never miss a day but I havnt started my period but a month ago I was on antibiotics an I hear that counteracts my birth control so on my birth control it says I'm supposed to start like in a week an a half but on here it says I'm a week late so Idk when exactly I'm supposed to start I've taken 4 tests all came back negative but with my not knowing when I'm supposed to start idk if it's accurate idk what to do