You are on the right track. In Bruce’s art and trainings, where and when does small frame get introduced?
There are 2 variations of Yang small frame. One is that small frame naturally develops out of Medium frame, when you no longer have to think and “you are not there”, plus the Qi is strong enough for you to just follow it, and the Qi takes over the movements. The Qi moves in small spirols and circles, and so the movements get very small, and sometimes are seen by an outsider.
Then there are a few Yang small frame sets, which are rare to find even in China. I learned one version in Shenyang, Liaoning, which I still practice. The stepping and postures are from a “power stance”, with no large, low movements, and it almost does not look like any Yang Tai Chi you might have witnessed previously. It is difficult, intricate and unusual. But, it is Yang Small Frame. There are a few qualified teachers spread out across China.
I hope the above was of use to you.
Best regards,
James, Baltimore County, MD