The following is not a medical advice, just what I personally do for my similar problems:
If she is doing everything right and she still doesn't lose weight, I'd check the thyroid. Also, for some women especially, if the estrogen levels are too high (and usually if you have PCOS, you have high estrogen), a reduction in calories might be needed, not just reduction of carbs. For me, who I'm small framed, if I eat more than 1200 calories per day, I don't lose a gram.
Regarding a Paleo-ketogenic diet (not plain keto), I think it will help lots. I have a few gynecological pains myself that are going away when on less than 40 gr of carbs per day for over a month (25-50 gr of carbs per day is the goal I keep). I also take a grapeseed/pomegranate/trans-reservator extract, and a curcumin extract, that helps with inflammation in these body parts (and they also lower estrogen).
And of course, it's not just what you remove from the diet, but also what you add: bone marrow broth, offal, coconut oil (very important in the keto diet), sea vegetables, live sauerkraut, and home-made goat kefir. If your patient doesn't go out much either, she should consider supplementing with 5000 IU D3 almost daily (which also lowers estrogen btw, among other major things it offers). These are not optional in my opinion. It's what I do to myself to get healthy from similar ailments. My superfoods: http://eugenia.queru.com/2012/03/05/top-10-must-eat-paleo-foods/
Regarding fertility btw, no matter what you might hear about dairy in Paleo sites, home-made GOAT kefir (24-36 hour fermentation, which means very little lactose, and different casein than that of the offending cow dairy), is the top "drug" you need: http://www.scientificamerican.com/article.cfm?id=real-males-eat-yogurt Kefir is 5-10 times more potent than yogurt, so as long as your patient AND her husband eat kefir, I'd expect good baby results. But it MUST be home-made (store-bought kefir doesn't contain all the needed yeasts and bacteria because of bottling regulations). More info about kefir: http://eugenia.queru.com/2012/04/19/a-word-about-kefir/
If she's trying to get pregnant (and if her doctor is ok with this, don't take this reply as a medical advice), she might need to supplement with folate (not folic acid, they're different) a few times a week too, about 3-6 months before she conceives. Especially if she goes low calorie Paleo-keto, where folate becomes less common in the food. http://chriskresser.com/folate-vs-folic-acid
I'd highly suggest she keeps a food blog, like on fitday or on Chronometer.com, to see which vitamins she's missing. Then she could supplement accordingly (but not overdo it of course, D3 and Mg are the most important ones).