Does NuvaRing's bad effects happen easier with more weight on your body?

I'm 17 years old, 5'4 and 220 lbs. I'm planning on going on the NuvaRing this weekend to help me remember to take birth control (or make it so I don't have to, more over). I've heard that with many birth control methods, it's not as effective if you have a good deal of weight on you. Will I be likely to get pregnant? My boyfriend won't ejaculate in me, but I know that every drop counts. Also, does being overweight make girls more susceptible to the bad side effects like stroke, embolisms, heart attacks, etc. I'm worried about those too. Mirena is out of the question because it has a high ectopic pregnancy and infertility rate. Are there any official studies/stats on the side effects of NuvaRing and who is mainly affected? Please detailed answers only and no vague one sentence answers.