I’ve never been able to get a good rise out of sourdough. I make bread all the time, make sauerkraut beer etc and my starter doubles in size but when making bread it just never works
My next attempt will include better, windmill milled flour.
Once you have a starter, keep feeding it with organic rye grain flour, you might need to try different brands. Bake in a cast iron pot, with lid initially, the crust will be unreal.