Try a 50/50 blend of ewc and good compost… not sure about your products out there so only speak from my experience with our local and home made castings and compost. So im sure someone can better advise according to where you are.
I add a couple handfulls of biochar to that too.
Remember your soil mix will have to cook for around 30 days to allow those amendments to break down to make them more soluble for the plants. As the microbes break down the amendments they create a compost generating heat that “cooks” the soil… you can turn it once a week until it starts cooling down. You will know when your soils cooking too cos it gets pretty darn warm.