Whole Wheat Blueberry muffins

I was so proud that I made blueberry muffins and they didn't come from a box! This is the actual picture Mark took of our muffins. Look how melty those blueberries look!
I used greek yogurt in place of buttermilk and I think it made the batter too stiff so I had to add a bunch of milk. I also substituted the whole wheat pastry flour for just plain whole wheat flour and a little white flour so maybe that was it? Either way, after adding milk they still turned out looking like this and tasting great!
http://deliciouslyorganic.net/blueberry-muffins-two-ways-gluten-free-or-whole-wheat/