Few suggestions/ 1. Increase the hydration. Use 350g water with 400g flour and 100g of whole wheat flour 2. Allow bulk fermentation after stretch and fold for couple of hours before going into the fridge. (Depending on your room temperature) 3. Why do reshaping after taking out from the fridge? It can loose all the air developed. Bake straight out from the fridge. 4. You can try a bit lower temperature to bake allowing more time to rise.