I was going to use progesterone cream and decided not to because the growth from progesterone seems to shrink back down as soon as you stop and I can't use it forever! if you are going to use it, you need to use it with a bunch of other stuff.
My friend used progesterone cream regularly for 2 years and grew 2 cup sizes, then she started to wean off progesterone by using smaller doses and within a couple weeks her boobs started shrinking again! She was also mixing shatavari with oil and massaging with it. But still they shrank as soon as she started cutting back on the progesterone.
And progesterone is what makes your boobs swell right before your period, but then they shrink again when your period starts. Progesterone is one of the main reasons why people's boobs swell so much during pregnancy, but again, they mostly shrink again.
I think progesterone causes water swelling in boobs, in order to try to replace that water with fat you need something else. Not sure what works best.