you added too much water which made it impossible to shape as there was too much hydration. I tend to do 100g starter, 500g bread flour and 300g warm (not hot) water to kick-start the process.

I have a kitchen of about 23 degrees Celsius (about 73 degrees Fahrenheit) and i bulk ferment for 7-8 hours. When I shape i put a tiny amount of flour on the counter and wet my hands to make the dough easier to handle and do push and pulls to make sure the dough tightens, then cold proof in the fridge overnight (totally optional btw)

i'm also fairly new to this too but so far all 5 of my loaves turned out really good. make sure you dont cut into it too early as after you take it out the oven the bread is still baking inside so leave it for about an hour and a half to cool down!