Antibiotics and Mirena?

Now I know we all have been told that antibiotics interfere with some birth controls making them non active for a while. I'm not sure which ones do that but I am on 3 separate antibiotics. My period is due to begin any day now literally. I've been having unprotected sex since I began the antibiotics...no signs of pregnancy but should I be extra careful while taking these meds just in case? I have 3 can't have any more well was adviced for least the next 5 years so.... Hence Mirena birth control.