After many failed attempts, I think I'm finally on the way to making good bread. I am very grateful for all the great advice I received here. These two loaves weren't perfect but texture and taste were very good. I need to work on my shaping skills. I think poor shaping is the cause of huge bubbles inside around the crust. I don't particularly mind them, it's more of a cosmetic issue for me.
I tried many different recipes and nothing really worked for me. I made up the quantities for these two loaves and they turned out pretty well. I also had to go through many overproofed and underproofed loaves before I realized using other people's timing just doesn't work for me, it is far more important to look at the dough than the watch.
Both of these loaves were made by autolysing everything except salt for 30 minutes. Then I added the salt and kneaded in a stand mixer on speed 2 until I could feel some gluten development. Again, I stopped looking at recipes for the times and instead tried to decide by feeling the dough (it took 5 minutes for the first one, about 8 minutes for the second one). Then I let if proof at about 18°C for 5 hours and folded twice during that time. I left the dough in a banneton in the fridge overnight, then let it sit at room temperature for 1 hour while I preheated the oven. Baked on a kiln shelf at 250°C for the first 5 minutes, then lowered to 220°C for the rest of the bake. Instead of steaming the oven, I covered the the loaves with a deep roasting tray for the first 20 minutes, then baked another 20 minutes uncovered. This seems to me to be a much better method that creating steam in the oven, which I was never really comfortable with.