I also have PCOS and my most successful weight loss effort ever was using calorie cycling. I did a version of the Up Day Down Day Diet and lost 50lbs. On my down days (low days) I ate low calorie and low carb. On my up days I ate whatever I wanted.
This worked really well for me for about 6 months when I hit a roadblock that was, in hindsight, probably more related to personal stress. (Financial...this whole thing happened when the economy tanked and my own personal economy was in a serious depression.) The stress got to be too much and the failure of the diet was really more about me not having my head in the game than it was about the plan itself. Due to the high level of stress, the high days got higher and higher and the low days got harder and harder, until I gave up.
Now, I am doing a similar plan but, cycling carbs more than calories. I really believe in the cycling theory because of past success and because I bought the book that Dr Johnston wrote (you can google JUDDD, a lot of the plan is online) But in the book, I read up on the science behind it. So, I understand better why it works. On a similar note I also bought one of the PCOS IR Diet books. I didn't necessarily follow either of the plans to a T...but as they say, knowledge is power. I learned some important things about PCOS, nutrition, balancing carbs with proteins and the science behind weight loss.
I also believe in the cheat day. It was the ONLY thing that kept me on track for six months. Most of my other weight loss endeavors only lasted a month or two before I started feeling too deprived. If I know there is at least one day where I can indulge, I can stick to the plan better all week. Maybe it isn't the answer for everybody. But, I do believe it works for me which is why I tried it again when I finally got my head back in the game.
I believe that is another important component of success. Eat less, move more sounds simple. Calories in, calories out, also simple enough. But, a huge part of your success in weight loss is mental. You have to figure it out and wrap your head around the idea. Invest in it emotionally. If you don't get there mentally; it will be almost impossible to get there physically.
Your PCOS body is going to fight you along the way, you--specifically the "yous" who are my cysters
-- have got to be mentally strong. It can be and has been done...even with obstacles like PCOS, diabetes, insulin resistance and/or hypothyroid. Most things worth having are worth working for and I believe our health is one of the things worth having.