I made my first sourdough starter 4 days ago, and when I checked on it today the starter had not started to bubble and froth and was looking verrrry soupy. Am I/ did I do something wrong? I made this starter the au naturel way, as in just bread flour and tepid water. Is the yeast/flour/water/sugar starter the better way to go? Or am I just being very impatient and need to wait a few more days?