What are the chances that I have PCOS?

My sister was diagnosed with PCOS last year, as far as I know, my mother does not have it. My sister has had irregular periods for most of her life since puberty, she has gained a lot of weight, but is now losing a lot of it. We always thought her symptoms were caused by the 4 years in which she was on depo provera, but we know now that she has PCOS. I have never really had irregular periods except for the 2 years that I was on depo provera, I have not gained nearly as much weight as my sister, (maybe 30 pounds in the past 3 years, I