Did my nexaplanon stop working?

I got my nexaplanon put in may 15th. We use the pull out method along with my bc and I test every four weeks after we have sex and they all come back Neg. It's been about three months since I've had it in since then I've never bled or spoted. But now, after auguest 15th (an exact three months since insertion) i'm having like a light period (not enough to get on pad but enough to cover tp when i do my daily cm/cervic check and amount of bleeding is becoming more). I'm having small cramps and the blood is orangish. It been going on about 3 days. Last time i had sex and we did pull out methid back to back was augest 10th. I know it takes three months for the body to adjust to the bc so is this my bady finaly ajusting to it or is my bc failing?