Hi everyone!!

I'm MTF, and have been on HRT for 3.5 months. Currently, my breasts each compose one large glad, that measures ~2 inches in diameter, and another gland, which has formed on top of the aforementioned gland; it has grown to around 2 inches in diameter as well. Of course, I have fat tissue up there as well, but not very much because I'm really skinny right now.
So, having said that, does the bulk of the female breast (at least in terms of appearance) primarily comprise these big glands that I have mentioned -- or is the aesthetic appearance of the breast mostly attributable to fat tissue accumulation in the breast area? Also, in regards to the glands I've mentioned, how big do they typically get?
See, the other day, my mom was making fun of my "grape" breasts and bragging about her "watermelon" breasts (lol). So, now I can't help but wonder if she has glands like I do, but that are the size of freaking watermelons (as opposed to ~2 inches in diamater), or if her big breast size is mostly attributable to her weighing around 50 more pounds than I do!
Thanks!
Alice