Wet dough

I'm not real new to sourdough, i make nice bread a couple times a week, but there are some problems i havn't been able to solve. Maybe you guys can help me out.  I've tried making bread with very wet dough, an it comes out very tasty, but flat as a pancake. I've watched vids on kneeding the dough an enjoy that process, but after fermenting the dough in the fridge, forming loaves, an final proofing, the loaves will not maintain their shapes from the banatons......they flatten right out. So does anyone know how to handle wet dough after the initial kneeding?? I would appriciate any insight!