Help me fix my flatbread
You shouldn't have kept adding flour. Baking powder recipes don't get kneaded, so they don't stop sticking. 

For troubleshooting, do follow the recipe exactly as given. Don't do any substitutions until you can recreate the original well. Even after that, if you want fluffy bread, the whole wheat flour will be a disappointment. 

And I doubt that you should be rolling it out at all. 1/2 cup of flour is 60 g, and 1/2 cup of yogurt is almost 120 g, resulting in 200% hydration. This sounds like a liquid batter more than like a formable dough, which is also consistent with the usage of baking powder. So, just pour it into a wide tin (well oiled, or lined with paper) and bake that way. 

If you really insist on rolling, you have to live with the fact that it is a very wet dough with little gluten development and it will stick a lot. So use techniques for rolling sticky dough, instead of adding more flour.