Hi Kate,
I’ve kept a strain of sour dough for 10 months. I killed the previous strain by adding teff flour. Too much too fast? not sure, but currently feed it with og white bread flour. I have a conventional/convection oven and an ooni pizza oven that uses wood pellets to make its heat. I’ve baked loaves in pans, free from on stones, made cinnamon and cardamom buns, and pizza crusts with oo flour. If you are short on testers, I am happy to throw my hat in the ring. I don’t make a lot of time for permies, but I think this community is a great resource. I’ve been to Wheaton Labs, and enjoyed meeting and interacting with the people there. It was there I learned that you can spread your starter out in a thin layer, let it dry, crumble it up, and use it to bake with like dry yeast. It is also a way to preserve the starter and you can start more from that powder too.
I can get any grain you specify. There are several botique grain operations within a few hours of my home that I can order from.