New to this OPK thing!! Help

Jo
Hey girls, I just did my first week of OPK during my fertile days and its all negatives. According to Glow i am suppose to ovulate today which I feel like its about right bc i have some creamy discharge since yesterday and also had light cramping, but the opk came back negative. Can someone tell me whats going on?? I just got off the iud paragard so it shouldnt throw off my O day right??