Honestly I think the results from these meds are very individual. You really have to learn to listen to your body carefully. I don't think anyone, even the smartest doctor on the planet can predict what sort of reaction or results a certain med will or won't have. If most docs (or experts on the internet) looked at my blood work they would say "You aren't going to see any results" yet I went from flat chested to very close to a full 34B and still growing. Others have been on max strength dosages with perfect blood work for years and still at AA size. Unfortunately a lot of it is trial and error, like finasteride caused depression for me, it doesn't bother others. Prometrium was a disaster, medroxy wasn't. I do not plan to stay on progesterone long but I do want to see if it will kick start some nipple development and maybe drive my T levels down some, the spiro isn't doing that. That was another weird thing, I'm on a pretty strong dose of spiro but my T levels are still around 200, almost exactly where they started at almost 2 years ago. Yet another thing that doctors don't understand..
I am sure that a study could show progesterone does nothing depending on the sample of patients used. A different set might show a big increase. I've read too many people who said their growth got stagnant and P kick started it.