If I may be blunt:
I've been on estrogen for 2 years and almost 9 months, and Progesterone in pill form for over a year. I've been desiring a full chest the entire time.
When I started HRT, the majority of cis women I encountered laughed at what I described (water weight, bloating, wanting to eat everything, and mood swings) and said "welcome to the club" instead of asking how they could help. I think they were trying to help, but in retrospect, I found it incredibly rude, dismissive, and condescending.
When I really started expressing the desire for breasts, no shortage of cis women came out of the woodwork saying their backs hurt and I should be so lucky. The night before my first consultation with Dr. Thayer in Muskegon, several people came on to my socials to complain about their cup size. They took my moment and made it all about them. When I asked them to knock it off because they were ruining my moment, they turned me into the villain. One accused me of hating all cis women.
So my advice to cis women: when a trans girl tells you she started hormones, listen first, and ask how you can help. When a trans woman tells you she's excited for a potential breast augmentation, spare her the canned "my back hurts and you should be so lucky" spiel. Don't be rude, dismissive, and condescending. You wouldn't want it done to you, so why are you doing it to us?
