birth control & fertile window??

This may sound dumb, but I've been on the patch for several months now. I've never been exactly sure what the fertile window entails other than high risk of pregnancy, but to be sure, there is no fertile window while on birth control, right? I've never had any issues with the patch before and have never been pregnant or had any major scares. I normally use a condom in addition to my own birth control and my boyfriends birth control implant. I'm safe, right?