Sounds like you are doing everything right. Does it have enough moisture, it should be like a damp sponge, but not wet and slimy. I have heard it also needs to be at least 3 ft high to really heat up. Also, what about putting some comfrey and nettles in your pile, and/or adding comfrey/nettle compost tea. I find these herbs help speed up the process. I have been to talks where the speaker felt that faster is not necessarily better as far as the nutrient levels in compost are concerned.