After child birth, no period & nuvaring

I have been diagnosed with PCOS for the past 7 years. The pill has always been a problem since I always forget. I had a baby 3 months ago and was on a period for about a month but have not had one since. I've taken multiple pregnancy tests and have been using condoms but I am ready to use Nuvaring. Since I have started, which I am use to, is it okay to start the nuvaring without having a consistent period?