My first sourdough

I think I did good for my first loaf! My starter is 12 days old! Was doubling day 6&7 within 6 hours and tripling days 8-11. Today is day 12.

Recipe:

100 g starter

350g water (warm ish)

500g King Arthur bread flour

10g salt (though it came out 13g)

Mixed starter into water, added flour then salt, mixed it until a shaggy dough.

Rested 1 hour.

2 stretch and folds every 30 minutes, 2 coil folds every 30 minutes

bulk fermentation on counter for 6-6 1/2hours when house is at 75 degrees.

12 hours in the fridge

Pre heated my oven and Dutch oven for 50 minutes

Ran out of parchment paper so I put it on a rectangular silicone mat inside my round Dutch oven after it preheated

Baked at 450 for 30 minutes then 400 for 20 minutes with lid off. Cooled 2 hours then cut!

I’m asking for feedback 1. Does this look okay? 2. What makes your sourdough tangy? Is it not tangy because it’s young or did I do something wrong?