Banana-Oatmeal Muffins -- 1st Attempt

This is my first recorded attempt at no-sugar, no-oil, vegan, 100% whole grain banana muffins.  I recall doing something of this sort last year in bread loaf form, but I can't find written evidence, so I don't know what recipe I used.  I just remember the flavor was good but it turned out a bit too wet from all the banana and didn't cook all the way through, which is why I'm making muffins this time.  It's also why I wanted to include rolled oats -- it seemed like they might hold things together as they hydrate and make the bread chewier and less dense.  If they still sort of fall apart, I'm going to try adding 1/4 cup wheat bran next time.  If they need to be sweeter, I think I'll have to add chopped dates or raw date syrup because they are significantly sweeter than bananas.  If they are too dry, I'll just add more bananas (or date syrup).  I tasted the batter before baking, and it seemed to have a slightly bitter aftertaste.  I think next time I'll reduce the baking powder to 1 tsp (and remember the baking soda).

I used this recipe from Saveur for an idea of dry measurements, but it was still kind of a crap shoot since I'm not using sugar or butter or eggs.

They just came out of the oven and are weirdly lumpy, though I'm not sure if that's because of the rolled oats or the lack of baking soda.  I'll post a verdict and outline plans for my second attempt after they're cool enough to taste.

Ingredients
1 1/2 cups whole wheat pastry flour
1 tsp ground cinnamon
1 tbs baking powder
1/2 tsp baking soda (which I just realized I forgot to include in the muffin batter -- I'm guessing this will make them denser than they would have been otherwise...?)
1/4 tsp salt
5 large bananas (why five?  because I had six overripe bananas on my kitchen counter, and one appeared to have gone bad)
2 tbs flaxseed meal
1 tsp vanilla
1 cup rolled oats
1 cup chopped walnuts

Directions

1. Preheat oven to 350 degrees F.  Line muffin tins with muffin cups.

2. Use a standing mixer (or very forceful arm) to beat bananas into mostly-liquid form.  Add flaxseed meal and vanilla.

3. Combine flour, baking powder, baking soda, and salt.  Add to wet ingredients and stir until just incorporated.

4.  Fold in rolled oats and walnuts.  Scoop into muffin cups and bake for 20-25 minutes.

[Edited 1/20/2015: These were surprisingly not bad.  The flavor was pretty good, obviously not as sweet as most muffins, but I will easily finish off the batch.  The texture was better than I've had with oil-free baking; I think the oatmeal helped a lot.  Next time I'm going to use six bananas for the added moisture plus sweetener, remember to include the baking soda, and reduce the baking powder to 2 tsp.  I don't think the kind of nuts used matters that much, but I do think their inclusion is vital to the semblance of normal texture.]