Birth Control Ineffective For Overweight Women?

I am in Birth control hell. I just recently read that Birth control is ineffective for women who are overweight. My situation seems miserable. I am a 28 year old woman who is on Ortho Novum 1/35. I am 5'8 and a 180 pounds. This is fifteen pounds overweight. So my birth control is in effective, I am assuming. Let me just say before I started Birth Control, I had PCOS, this was due to a combination of factors. Cross-Country running, lose of Menses, and overall bad diet. However, what is interesting is that when I was running I was at the target weight for BMI calculator at 160 pounds. I do not feel that 160 pounds is an ideal weight for me. I had a loss of my menstrual cycle. Overall I felt like I was too damn skinny. Now at 180 pounds I feel like I am a little healthier. I am wondering if maybe the extra weight is due to muscle mass in my legs. Forty pounds of muscle in each leg. That equals out to eighty pounds, and a hundred pounds from overall body weight. Maybe I should do some kind of exercise like pilates that focuses on small muscles instead of the large muscle. I am just worried, because putting it discreetly it looks like I might be more sexually active.