First sourdough loaf – any wisdom to help me improve?

I have just produced my first sourdough loaf. I have been studying for a while the best way to make it, and after many YouTube videos, I have decided to follow the recipe from Alexandra Cooks: https://alexandracooks.com/2017/10/24/artisan-sourdough-made-simple-sourdough-bread-demystified-a-beginners-guide-to-sourdough-baking/

I have used water filtered with my Brita and flour with 13% protein from Caputo.
Bulk fermentation went past 150% because it started late in the late and I prioritised sleeping 🤪 I proofed the dough in the fridge for about 12/13h.
Scoring was a challenge since I didn’t have any sharp razor.

Overall, I was quite pleasantly surprised with how it turned out. However, I realised that the crust was elastic and not hard, making it hard to have a clean, crumbly cut. Could this be from underbaking it in the last stage?
The loaf inside was soft and chewy (in a nice way) – which I believe is linked to the high protein content in the flower.

I am happy with the taste, and really enjoyed the process. I plan to test the beginner method from The Perfect Loaf, but would love some tips 🥰