Looks like Van beat my post by a few seconds. At any rate, my take is about the same as his. My first guess is that you're eating way to much protein, given the diet you listed. When we eat more protein than out body needs, our kidneys turn the excess into sugar. When we have sugar in our bloodstream that we don't need for fuel, our bodies can turn it into fat and store it. If we don't get much exposure to cold, this will likely be white fat, which is slow to disappear because it's not metabolically active.
My advice, as unpleasant as it might sound to you, is to make some substantial changes to your daily diet. I'd first suggest adding in a little carbs, as they can help convince the body you aren't about to starve and keep your metabolic rate up. Eating carbs from raw root vegetables like Jerusalem artichokes, onions, sweet potatoes, beets, etc. will add a lot of fiber to your diet, which your gut bacteria will turn into short chain fatty acids. These make great fuel, and will help to coax your body to burn more fat as fuel. My next suggestion is to reduce your protein intake to just barely what your body needs to replace/repair muscle and other tissues. There are equations you can use to estimate what this is. My guess is that for you it is probably no more than 6 ounces of meat/organs per day. The rest of your calories should come from fat.
Getting all of your daily calories from fat and carbs will likely involve eating a lot more fat than you're used to. It might mean eating a stick of butter every day if you're into dairy, or eating a sizable chunk of suet or back fat from a grazing animal if you can get it.
I would also suggest regular cold exposure, especially on your upper chest and upper back. This will turn your white fat into brown, metabolically active fat that has more mitochondria in it. The more brown fat you have, the easier it will be to burn fat and to reduce your body fat percentage. You can start with cold showers, then you will probably want to transition to ice water baths or swims in cold (under 50 degrees F) streams or lakes.
Good luck!