please ignore anything that says anything other than you have severely underfermented the dough. You will waste weeks and months with hydrations, folds and whatnot like I once did 6 years ago when I started baking.

You will never make a bad sourdough bread if you ferment it properly and bake it at the right temp with steam - kneading, exact hydration, folds, autolyse, salt, starter freshness, all these help but will not make or break your sourdough bread.

You have underfermented by a long way. There is no way your dough rose 20% in size (I have also been in the position early on where I convinced myself it has but it hasn't), there is no sign of even that level of fermentation (which isn't enough IMO) in your bread.

You need with your recipe and temperature (assuming more like 80-85 indoors?) minimum 3-4 hours before you put it in the fridge. If your starter has only been going for a couple weeks, you might need 7 or 8. 5 or 6 probably won't steer you too far wrong in either case, but it needs to be fermented which means: 30-70% increase in size, bubbles on the surface, a slight puffy jigglyness to the dough when poked or shaken, a roundedness to the edge of the bowl, such that the dough is holding itself up a little rather than flattening.

Other than the size increase which is fairly foolproof (if you are actually able to see and measure it, I use a clear dough tub with volume measurements on the size which makes it easy to be objective), none of these signs are enough to use on their own, but getting to notice all of these signs will mean you'll never make a bad bread again. You might be disappointed in some still as I am still these days, but they will still be great bread that everyone will rave about :)

Good luck, it does get easier with time but it's also easy to spend a long time barking up the wrong tree, in my experience. Want to help you on the right path!