I've been on various brands of birth control (pills) since the middle of 2008 and I started using NuvaRing on August 15, 2010. My last birth control ("fake") period lasted from January 26-29, 2011, and I didn't insert a new NuvaRing on the 30th (the normal day I would insert a new one). On February 19, I had unprotected sex. NuvaRing works on a 28-day cycle; 3 weeks in, one week out. So on February 23, I inserted a tampon because I thought I might get my period, which is the normal time I would expect it while on NuvaRing. Late that night I took it out and there was a very small amount of blood on the tip of it, but otherwise I haven't had any other bleeding. I've been feeling quite nauseated for a couple days now (maybe since the 25th?).
Here are my reasons for why I think I'm pregnant: I've read that ovulation can start 13-28 days after stopping NuvaRing, so there is a chance I was ovulating by February 19. Also, the bleeding that occurred wasn't "normal" withdrawal bleeding. The little bleeding I had would probably have actually leaked out (if I hadn't used a tampon) by the next day (February 24), and I've read that implantation bleeding can occur six days after conception, which is only one day later than my bleeding.
So, what are the chances of me being pregnant?