Pregnancies on Nuvaring?

I was wondering if anyone has ever had a pregnancy while on Nuvaring (and taking it on time, inserting it correctly, etc.). I've been on other birth control in the past but I'm still trying the one that works best for me. I'm in a monogamous and long term relationship (and I get std tested annually just to be on the safe side) so just wanted to clear that up before people start getting on my case. I've tried the implant (had horrible side effects), the patch (kept falling off and severely itched) and we use condoms as a last resort but prefer not to use them if possible. I'm debating getting Nuvaring but have heard of pregnancies even with perfect use. Whatever I get has to be really effective bc my boyfriend does finish inside me and I can't be getting pregnant for awhile (I'm only 17 and I'm starting college soon)