Hi there,
Nuvraing is effective if it is inserted into the vagina and left in place for three weeks. After three weeks the ring should be removed and during this one week ring-free break the levels of the hormones in your blood drop, which results in a withdrawal bleed. If the ring was left in for more than four weeks, then it becomes less effective and you may need a pregnancy test .You may need to use condoms or not have sex for the first seven days after the new ring is inserted. It is best to visit a gynecologist and get your doubts clarified since you have not been using it as prescribed. Do write to me again with more queries.
Best luck and regards!