I don't have PCOS but I have a cyst and have had hormonal imbalances and am overweight. Since last November I have been almost Paleo, on a low carb, high protein, no-gluten, no-dairy, no-soya diet. It is partly to get rid of the weight (of which I've lost over 6 stone now) but it has also shrunk the cyst alot so I am hopeful. A friend of mine with multiple cysts went on this type of diet and all her cysts went.
I have no caffeine and little processed food (although sausages are my weakness). Also no sugar.
My diet is probably a little extreme, but I have other health problems. I would recommend no soya, and low carb with lots of fresh natural food and veggies. Fertility yoga might help but don't know if it's ok to do with PCOS.
I've also read that candida can mess with hormone levels and cause PCOS and fertility problems, which is why a low carb and low sugar diet works for some people. Don't know if that is true.