[The First Aria]

Basically Prog develops the milk producing structures, which you can't do until you have the basic breast tissue that E gives you

Maybe, but many doctors feel that no Prog is needed for MTF.  They say in CIS Women, it only sloughs of the uterus wall during menses and help with child bearing.  So, IMO, no one knows for sure other than it took my T from 200 down to just 5.

Whatever the quacks may say, I KNOW that Prog had a positive effect on my volume. I grew  on PM alone but they were narrow with a wide gap in the middle. Then I took Microgest for only a few months but I could definitely see an increase in volume on top and in the middle. Didn't fill the gap but definitely reduced it.

I'm not in disagreement, as I am on Progesterone as well.  Besides, if anyone did "due diligence" on research they would find that CIS Women at puberty is loaded up with both E and P...  If I remember what I read on the white paper from John Hopkins University Med Library....  Almost 2x normal E and 3x normal P than women after puberty.   There has GOT to be a reason why that is.  But a bigger question is why don't doctors try to mimic what nature does..  After all, isn't that what a TG is doing?  Re Birthing and going through puberty as the opposite sex???