Beginning Baker Loaves not Shaping up

     I am fairly new to baking.  As I was getting started I was using King Arthur recipes (https://www.kingarthurflour.com/recipes/six-grain-bread-recipe and a white bread recipe).  I never had any issues using them and have always had decent results.  The taste was great.  My only issue was the crumb was a little dense.  

     I just finished reading Flour, Water, Salt, and Yeast.  I am waiting on my dutch oven and a couple other things so that I can work through the recipes.  I figured I would try some of the techniques and adopt them to the recipes I've been using from King Arthur Flour.  I have made a six-grain wheat and a white bread.  The things I've changed were:

• I dropped all ingredients other than Flour, Water, Salt, and Yeast.
• I made sure that the hydration was at 72% and used less yeast to slow the rise.
• I used the pincer method and three folds for the wheat and the two folds for the white bread.  In the past, I had been kneading by stretch, fold, ruling.  
• I baked on a higher temperature and used some foil for the first half hour of baking and then took it off for the last 20 minutes.  

     This has been the best tasting bread I've ever made, the crust was better than I've made, and the crumb was exactly what I have been trying to get in my bread. My only issue and i'm not sure if this is an issue was, I waited until it tripled but I when I shaped it into a loaf and it barely filled the pan.  Even after it had risen in the pan and was ready to go into the oven it wasn't even close to even with the edge let alone rise up an inch over.  Is this because I didn't generate enough gluten during the mixing and the folds?  There was some tearing and a lot of sticking as the dough was coming out of the mixing vessel when I was getting ready to shape.

Thanks for any help or advice.