I think it depends a lot on genetics. I started at 135 and was down to 125 after a month of HRT (muscle loss probably). I stayed at around 128 for 4 months and my body was seeming to replace muscle for fat, and then recently in the past month I've been trying to gain a little weight to see where it goes. So far, I've gained a healthy 8 lbs and it's nearly all gone to my butt / thighs. My tummy looks basically the same as it's always been. I've never been overweight though, so maybe the whole cell memory effect does hold true.
Either way, I'm kind of okay with gaining even a bit more. Towards the end of this year I'm going to do fat transfer to the hips, so the more I have to transfer the less likelihood I'll need implants to make a sizable difference. I'm still well within the healthy range for 5' 7" with a medium/small frame so a little more couldn't hurt 😉