I wouldn't throw in the towel and go primal weight-watchers just yet. Check this check-list. If you pass the check list then you can go primal weight-watchers.
-Total body nutritional sufficiency? Good that you're taking magnesium and vitamin d, but what about others like potassium that tend to be low on low carb diets? That includes iodine. A lot of people are deficient in good iodine. We'll automatically have hypothyroid if we have too little. Various toxins just make the problem worse. You say you have no thyroid issues but we can never be sure that the lack of a diagnosis means that everything is all well.
-Total amount of omega 6 in diet? What kind of fish oil are you taking? I'm really not a fan of fish oil, simply fatty fish cooked lightly. Sometimes with fish oil all it ends up doing is causing oxidative stress or suppressing the immune system, or nothing at all. The way to improve cellular DHA status is truly to eat fatty fish.
-Gut health? Have you considered trying as hard as you can to heal the gut? Gelatin helps and a good quality probiotic is important. Combine that with fermentable fiber like chicory root of jicama to help heal the gut and produce butyrate to improve insulin sensitivity and decrease inflammation.
- After that, Try a higher carb intake to the tune of 25% calories as mostly starchy carbohydrate before trying a low calorie diet. It's amazing how some people respond to good primal carbs. Often it resolves cortisol issues that some people get on a very low carbohydrate diet.
-How are exercise and sleep? How is temperament?
If you have tried all of that, THEN maybe try less calories but I don't like that. It just ends up causing problems and misery down the road and treats the symptoms of a problem that should be taken care of anyway. You have a history of weight watchers and I would count that as a potential metabolic antagonist. Our brains loath being starved when they are already starving due to poor leptin signaling. If anything you should probably eat more food and work on health instead of making a goal as quickly as possible.