glad to hear about your progress. I start to believe I'm hopeless at backstroke :) Guess I've tried almost everything but nothing really seems to provide the breakthrough I expect. Why I expect a breakthrough? For me, swimming 100m in 1:30 at fs is easier than swimming 100m in 2:00 at bk. If I relax my pace drops to 2:15. Comparing to fly, which is a stroke I never practice: my easy fly is way faster than my easy bk, I can easily stay under 2:00 on 100m, or I can swim 50m in 50s with a reasonable effort. No way I can hit 50s over 50m at bk, even at max effort.
The things you describe seem fine tunings more than anything. Instead, since you started practicing bk, is there something that you consider a cornerstone, that made you instantly faster once fixed? (eg fix balance and jump from 2:15 to 2:00 effortlessly)