PSA: check your oven door thermometer before you blame your starter
I kept getting dense loaves with a pale crust for 3 months and nearly threw out my starter twice. Last Saturday I put a $9 dial thermometer on the middle rack and found my oven runs 40 degrees cold, which meant every bake was under proofed and under baked at the same time. I bumped it to 465 instead of 425 and the same recipe finally gave me the spring I wanted. If your bread keeps coming out flat, spend the $9 before you spend another month feeding flour to a jar. Has anyone else found their oven was off by that much, and did you get it fixed or just learn to add the difference?