Your age does affect your ability to lose weight, imho. But it doesnt make it impossible.
I think that if your starving yourself, as opposed to sensible eating and exercise, then your body will go into starvation mode. It slows its metabolism right down to exist on the food it does have. When you eat a bit more it then stores as much of it as possible as body fat to get it through the next "famine".
What you dont want to do is mess up your metabolism to the point that your not burning fat effectively.
Blood sugar control can be a problem for PCOS sufferers iirc so perhaps the low glyceamic index diet would suit us better than calorie control diets? eg being sensible all day is all very well and good but if you then have a sugary pudding at night your blood sugar levels will shoot up which isnt really ideal for us. Plus sugar is very ageing to the tissues in the body even at cellular level. It literally makes the tissues toughen up and age. With a steady supply of carbohydrates you should, theoretically, be able to go between meals without that snacky feeling. All starch breaks down to sugar it's just a matter of controlling the speed of absorption. E.g fruit is loaded with sugar but the fibre in the fruit slows the rate of absorption down. Where as a chocolate bar's sugar has no fibre in it so breaks down very quickly.
When I bought the zita west ivf book (and I assume it's the same for normal conception) she adivsed giving up saturated fats such as margarine, vegetable spreads and butter. I lost 9lbs literally overnight. I use olive oil and goose fat in cooking instead, neither of which are saturated. You dont miss them after a while.
I also take Solgar Kelp tablets, they contain a lot of iodine in a one a day tablet. I dont think it hurts to take it, I didnt take it for weight loss but hair growth as I had all my hair cut off and wanted to encourage growth. It is meant to be good for metabolism though, especially if you dont add salt to food (I dont).