Why does my homemade sourdough bread always fall flat, and how can I improve its texture?

I totally understand your frustration! I've been there too, and it's great that you're not giving up. One thing that might be helping your bread fall flat is overmixing the dough. Sourdough bread is all about creating a delicate balance of yeast, bacteria, and flour, and overmixing can disrupt that balance. Try to mix your ingredients just until they come together in a shaggy mass, then let the dough rest and develop on its own.

Another thing to check is your oven temperature. Sourdough bread needs a hot, steamy environment to rise properly, and if your oven is running cooler than you think, it can affect the texture of your bread. Try investing in an oven thermometer to make sure your oven is at the right temperature. You might also want to try baking your bread in a steamy environment, like a Dutch oven or a steamy oven with a pan of water inside.

As for the type of flour, I've found that a high-protein flour like bread flour or all-purpose flour with a high protein content works best for sourdough. Some people swear by using a type of flour called "Type 55" or "French bread flour," but honestly, the most important thing is to find a flour that works for you and your starter. Don't be afraid to experiment and try different types of flour until you find one that gives you the results you're looking for.

Lastly, don't lose heart! Making sourdough bread is a process that takes time and practice, and it's normal to have a few failures along the way. Keep at it, and eventually you'll develop a starter that's strong and healthy, and a bread that's light and airy. Good luck, and happy baking!