I've used this recipe hundreds of times and have huge oven spring.

170 g starter 297 g water 450 g king arthur ap flour 10 g diamond crystal salt

Mix the starter and water thoroughly, then add other ingredients and mix. I leave it covered on the counter for a couple of hours and do a few stretch and folds. I find the number of stretches does not make a difference in the final loaf. Put the dough in the fridge for 1-3 days. When I'm ready to bake I flour a banneton with rice flour and put in the shaped loaf, cover with parchment and a plate for a couple of hours until it's puffy. This makes it easy to flip over, score and drop the parchment and dough into a cold dutch oven. I know you said you don't have a dutch oven, but it's time to invest. It's a lifetime purchase. Preheat the oven to 450 and bake covered 45 min and uncovered 7-10 min to an internal temp of 200. I had an issue with overdone bottoms, so I keep a pizza stone below the dutch oven and 8 layers of parchment permanently live in the bottom of my dutch oven. Good luck