sourdough with oats, stout, cheddar, and onion

For my second sourdough loaf I tried this awesome recipe:

http://weightloss-slim.fit/node/59838/stout-and-2year-old-white-cheddar-sourdough-oats%3C/a%3E%3C/p%3E%3Cp%3E%C2%A0%3C/p%3E%3Cp%3EI followed it pretty exactly, but added caramelized onions and 1/4 tsp instant yeast. I still want to work on getting a slightly better oven spring and more open crumb, but it tasted amazing! I'm still trying to figure out if I am over proofing, under proofing, or not developing the gluten enough.