How did you know you have PCOS?

Just curious about those of you who have been diagnosed with PCOS, what were some signs/symptoms you had? Husband and I have only been TTC for about 6 months after having the nexoplanon fr 2.5 years, but I just have a sneaking suspicion that I may have PCOS, I don't know why! 
I always read about SUPER heavy periods and painful cramping, but I actually have the opposite. Very light, short (2-3 days) periods and virtually no PMSing or cramps. I've always been a bit heavy, but in the 4-5 years I've gained a significant amount of weight and CANNOT lose it. I've read weight gain/trouble with loss can be a sign? I'd just love to hear other people's experiences!