Baking and baking and not improving! : vimarsana.com

I think I bake sourdough bread for 2 years now and I have never had a perfect oven spring or big ear. Basically, my bread doesn't grow up, sideways only. Now, I am trying to analyze what goes wrong. My recipe: 80g starter, 300g water, 360g bread flour, 40g whole wheat flour.1. I am mixing levain in the evening, so in the morning it's ready to use. I make 1:7:7 mix, keep it in