Corset training is a huge pain, but when performed correctly, not to an extreme extent, with a good corset, it's safe and reduces the waist, giving the impression that hips are larger.
Apart from that, HRT helps, but especially if you're too old (which seems to be 25 on average), it might be only fat-wise. Regarding that, the only thing you can do, I guess, is try to burn the belly fat and put some on in the hips. How? Mysteries of life. Might be easy; might be hard. Just look at how some women diet and lose breasts, then put on weight and gain belly.
This is just personal experience, but being on a high dose of anti-androgens and way too low a dose of estradiol (so my levels are probably what they are in a ~10-year-old girl), there's barely been anything related to oestrogen, EXCEPT my hips which have grown enough for my previously perfectly fitting pants hurt like heck at the hips and I can't wear them anymore because of that. (The most expensive jeans in my life, guuuh.)
So maybe, just maybe, cutting off all the T and putting in just a little bit of E for a while promotes hip growth. Though I'm still looking forward to my appointment with the endo very much. I want the rest to start moving after 6 months.