I am trying to grow my starter for the very first time. I have two of them, one is 12 days old now, 100% hydration white flour at 1:2:2 ratio, feeding every 24 hrs; it's a little bit bubbly and not rising much, not more than 10% of its size. The other one is 10 days old, also 100% hydration, a mix of white flour and whole wheat at 1:1:1 ratio; it still has some bubbles but not much of a rise.
Both smell yeasty with a hint of acidity. My kitchen temperature is around 20 degrees. I wonder what I am doing wrong. I read that by now my starters should be doubling or even more.