Please participate in our “Let it Snow” Xmas 2020 Group youtube project!”
Glad to hear things are going better. I find C natural harder than C# too. But I've noticed that most beginning lessons start with that "high 2" fingering. I think it is easier for most people.
Supporting your violin with your hand because it felt like it was falling likely added tension, making it harder.
BTW, I found this exercise from Julia Bushkova, and have begun doing the first part. It is surprisingly difficult, but I believe it will help me with these sorts of issues as I learn new finger patterns: