I've tried men's pants a few times over the years of my transition (pre-t, months on t, years on t) but always had the same issue as you. I'm at a healthy weight for my height now, but need a waist size of 34 inch of men's pants to even get into them, and then they have a huge gap at my tiny waist that is very obvious. And then also their "straight cut" jeans fit very tight around my butt but are looser than a tent on the rest of my legs. Also trying to even find pants in waist size 34 with leg length of 28 is a conundrum.
So actually I stopped trying to wear men's pants. I wear women's pants now. Simple, low waist, straight cut, plain black pants. They fit my body and just look like any kind of pants. They don't look womanly and whenever I've told people that they're actually "women's pants" all they've said is "no way".
I know it can be dysphoria inducing to wear the clothes of the wrong gender when transitioning, but sometimes that's the best bet. I can wear men's shirts, jackets, underwear, gloves, hats, etc. But have to stick to wearing women's pants, shoes, socks, waistcoats, etc. cause of my body shape and how the different garments are meant to fit.
I only have two belts, actually. One of them is a simple wide one in black leather with a silver-metallic buckle. It's super long with many holes in it, so I can wear it whatever weight I'm at. That's great for me who can't maintain my weight to save my life. The other belt is similar but studded, so that's more "metal guy" style, I guess.
My hips never did slim down enough on just T, but then I never did work out much either, and had a bad starting point. I did learn how to dress to hide them though. I've been on T for 5+ years now, and have no issue passing.