What can I say except that you have been blessed in your ability to build muscle and of course the dedication to put in the hard work, too. Your upper body looks astonishing!
I find your posts to be very motivating. I've now been lifting for a year and the change in mindset going from "I'm chubby and pasty" to "I'm a beast" is a trip and a half. While I was never obese, I was very curvy, which in my head is kinda the same thing but of course my circumstances are a bit unusual. But I do think that I can at least in some ways relate to the mindset of a guy who used to be the size of a micro car and who's now visibly athletic and strong as hell. Like, while I operate on my natural estrogen-heavy endocrine balance still, it's such a great feeling to notice that my body is bulking up and feeling harder/more solid.
And while I'm no sports scientist, I bet that people who used to be very obese and women/AFAB people share certain benefits when it comes to body building. As you said yourself, carrying that extra weight around has made sure your lower body is strong AF, same with folks with lots of estrogen, the legs just basically build themselves. And of course building muscle requires a shit-ton of energy that's readily available in adipose tissue, so lifting really, truly is the best thing a fat person can do to work towards a healthy body. I know I'm rambling but what I'm trying to get to here is that our species developed the ability to get fat for a reason, and the sooner we stop shaming fat people and tell them/ourselves that we are unhealthy, and instead put all that energy towards realizing that fat is just an energy storage that can be put to good use, the closer we are to ending the obesity epidemic. Weight on it's own is just a bad metric of health; it can give a rough estimate of what's going on, but that's all. According to the BMI, I am currently 20kg overweight but you'd never be able to tell just by looking at my body. Muscle weighs a LOT. I have gained weight since I joined this forum but I can tell by the way my clothes fit and what I can do with my body that this is the right direction to go in.
Sorry about the weird waffle. I'm just so happy for you and how you clearly thrive and derive joy and pleasure from you physical ability. Your arms and chest look absolutely gorgeous, I hope that's OK to say (if not, I'll edit it out!).