Birth control & Macrobid

It may interfere with your birth control. Although there is no proof that it it does, it is thought to have the ability to do so. (Nitrofurantoin - Brand names: Furadantin, Macrobid, Macrodantin, Nitro Macro)

Contrary to common wisdom, only certain ones do for sure, and some are thought to be able to do so.

Your risk is likely very very low (you have been on BCPs for a while, it is only thought to be able to interfere, he did not ejaculate inside you, it happened a while ago), but you need to speak to your doctor about it if you are worried.