I've made several different loaves of bread with different recipes, but always get a tight, store-bread type crumb. My starter very readily doubles or triples itself, but something seems to stop working when I mix the dough and knead. I have no mixer, so everything is done by hand. I also try as hard as possible not to add any more flour than necessary when kneading or folding so things don't get too tough. I would be happy for any ideas or suggestions!