For what it's worth, I've been baking Sourdough breads for close to 30 yrs now.
Think of your starter as your yeast maker, it's main purpose is to rise the bread.
The more sourer the starter is the less it will rise the bread because you have let the yeast die out and let
the sourering stuff take over (hope that makes sense).
What you want is a very fresh starter, fed to the point that it will double it's self in 4 hrs.
then add this yeast fill starter to your mixture of Flour and water to ferment, the longer "this" sets is where
your sour flavor gets going, of course the trade off for sour is less rise, so look for your balance.
In pizzas you may not need alot of rising power.