I started spiro about two months ago, and estrogen a month ago.  Over the weekend, my nipples were suddenly extremely sensitive, and today my nipples are decidedly puffy.  Not poking through my shirt yet, but this is suddenly happening very fast.  I feel like I'm gonna have a pair of golf balls on my chest by next week, and since I have no body fat, this is going to be very obvious very soon.

I have a nonbinary identity, and I'm not entirely sure how feminized I want my body to be.  I've been feeling like a million bucks now that testosterone is out of my life, but as I see it, it's now or never if I want to stop and not deal with breasts for the rest of my life (or a mastectomy, ugh).

What would happen if I were to stop now?  Would it have a permanent impact on my body's ability to grow breasts, or will breast development just freeze and resume when I restart estrogen?  I can't imagine there's much scientific literature about this, but enough people seem to start & stop HRT that somebody around here might know.

Don't do anything unless you get the green light form your doctor.  Sudden shocks to the endocrine system can have butterfly effects on other systems and affect your thyroid function.

Yeah, my 1-month checkup is next week... ooh that reminds me, I should schedule that today.  I wish she was an expert in this stuff.  She's just blindly following the WPATH guide to make me a woman... which doesn't really fit... *sigh*

I too was concerned prior to starting HRT. My therapist said just give it 4 months and see if it is right for you. After 2 months I told her I would never go off HRT.

Everyone is different and have different needs. So if HRT is not for you then discuss it with your doctor before doing anything.

No one can give you assurances about how your body will react to HRT including de-transitioning. In general I have heard the first three months are reversible. I do not know this as I never de-transitioned.