If you've just made some a loaf of extremely dense bread that also doesn't seem that sour, you may have lacked sufficient yeast in the starter. While some folks avoid sweeteners like these, they do contain concentrated sugars that'll kickstart the fermentation process. Some bakers won't bother with this step, but it's certainly a good idea. Although you can make a functional starter without sterilizing, you may have other microorganisms growing in there which could impede the growth of the airborne yeasts.
Less yeast means less rising.
Less rising produces an extremely dense bread, which many bakers avoid making and many people avoid eating. Find a large saucepan or pot that can contain the starter jar. Place the jar in the pot to test the size, before you go any further. Using rubber gloves or kitchen tongs, pick up the jar and submerge it in the boiling water. Also drop in the spoon that you'll use for stirring.