Robb, consider what type of fluffy white bread you're after and look specifically for such a recipe e.g. Japanese milk bread and challah (especially if you use liquid oil as the fat and honey as the sugar) are fluffy breads. Use a bread recipe that gives measurements in weight, and weigh your dry ingredients. It amazes me how different flour brands give me different weights per cup! Check that your yeast is not expired, and create a yeast-friendly environment (ingredients should be about body temperature; if too hot it will kill the yeast). Knead until the dough is satiny - 10 minutes in a stand mixer. After the first rise, be gentle with the dough when deflating the air and shaping the loaf. Cut baked bread when the entire loaf is cold.