In a small bowl, stir together the flax seed and water. Set in the refrigerator for about 5-10 minutes.
Preheat oven to 375 degrees F. Line muffin tin with paper liners and set aside.
In a medium bowl stir together yogurt, agave, vanilla, lemon zest, lemon juice, and flax+water mixture.
In another medium bowl stir together whole wheat flour, oat flour, protein powder, baking powder, baking soda, chia seeds, and salt. Pour dry ingredients in with the wet ingredients. Mix gently just enough to combine. Add blueberries and gently fold until evenly distributed.
Using large ice cream scoop, fill muffin tin with batter, 3/4 to full for each muffin. Bake for 19 - 21 minutes or until toothpick inserted in the middle of the muffin comes out clean.
Remove from the oven and let cool for 5 minutes. Transfer to a wire rack to cool off completely.