Fantastic! We absolutely love his writing here.

Right here!
https://www.theperfectloaf.com/7-easy-steps-making-incredible-sourdough-starter-scratch/

Hey, Eloisa! I’ll answer, if I may.
– In my opinion, an old sourdough starter is just as good as a new one. They’re both going to have different strains of yeasts and bacteria, but as long as they’re showing signs of strong fermentation, both will leaven well.

– See my guide to proofing, here: https://www.theperfectloaf.com/guides/proofing-bread-dough/

Fresh yeast is a type of commercial or instant yeast. I personally don’t use this either, only sourdough!

A gummy interior can be several things. If the hydration is too high for your dough it can lead to an overly wet or gummy interior. If the dough feels “soupy” or very “slack” then try pulling back the water percentage by 5% and see if that helps.

Make sure to bake your loaves completely. The interior should register around 204-206°F (95-96°C) or higher.

If your loaf is under proofed then this will typically lead to a gummy or “wet” textured interior. Make sure your starter and levain are very vigorous and strong when you use them. This is very important! From there, make sure to bulk ferment your dough fully (use the images you see in my posts to guide you on what the dough should look/feel like). You want the dough to be alive and aerated before you divide and shape.

From there, a full and complete proof is also very important.

A few ideas there for you, let me know how the next attempt goes!