You just need to control your heating from going out from yoiur home. For this you have to capture your heat. There must be something that can surely do it. Yes, you are right, you need proper internal wall insulation. It will ban your heat to go out.
Overall, insulation is a great way to make your home more energy efficient and comfortable. It’s like adding a layer of protection against the elements, so you can enjoy a comfortable temperature all year round.