It’s largely reversible in the first six months or so. Generally breast growth is not reversible and for some people that takes a while to start but for some it begins to happen sooner. You could try it for a couple of months and stop if you feel tender nipples, which is a sign of breast growth activity. Though my biggest changes have come a year in to the hormones due to the way they ramp things up over time. I was taking 2mg E per day at the start and now I’m taking 8mg E and 200mg progesterone (which helps suppress testosterone), so my experience now is much stronger than it was a few months in.

Very interesting. Thank you for sharing your story and participating in the discussion. I looked some of these things up with a search engine, but do not know what to trust. Regarding progesterone I saw a few places assert that it increases testosterone (example link below), but it did not discuss the mixed case with E(strogen) you mention.

https://pubmed.ncbi.nlm.nih.gov/15669543/

Some doctor experimented by dosing themselves with progesterone, and found that after a few days it increased their libido significantly, but is completely reversible otherwise.

Depending on method of administration, changes occur sooner or later. A common one is "monotherapy" with only estrogen injections in oils which get released over time.