Losing boule shape during baking
Hello! I am new to this forum and fairly new to sourdough baking (20 loaves in). The pics are fairly typical of my efforts. What starts as a boule before baking ends up more as an oval. The dough expands more at the belly so expands outwards (away from the ear making the oval, and sometimes parallel to the ear forming outward bulges), whilst the thicker crust holds firm. It's not a disaster but, out of interest, can anyone suggest how to get it to stay rounder during the baking? Thank you, and sorry in advance if this is in the wrong part of the forum or a stupid question.