I've been a range of sizes and shapes over the years and I've never been great at shopping for pants. I'm 5'6" and probably 180ish pounds. When I was younger I was a bit more than an inch taller (some injuries and surgeries since then) and ran 100-135 pounds. Even when I was super skinny, my actual pelvis is very wide, so I've always settled for pants that are too long. I usually roll them up or cut them and let them be ragged, but if I need to dress nice for court or an interview then I cut and sew up the bottoms. Safety pins don't look too bad if you're in a hurry.
As far as what department to shop in, I've never really felt at ease in any clothing department of any store. My physical transition started slow and I often had that problem of salespeople trying to redirect me away from where I'm shopping. I have shopped in women's and female juniors, I spent most of my life shopping out of the male juniors, and after going on T and antidepressants I gained enough weight to get out of the kids' sections and into regular mens. Still nothing fits me great, but employees don't bother me anymore.
I solved the acquisition problem the same way I did when I was younger and shaped differently - I find a pair or two that I like, or that are even just good enough, and I keep wearing and mending them as long as I can wear them and still breathe okay. I don't pay for new clothing unless it's an emergency (like work uniforms), and I get most of my pants from thrift stores, free piles, friends, garage sales, or garbage bins near consignment shops.
You have to grit your teeth through the funny looks if you purchase your clothes (new or used), though, and try them on if at all possible. It's just as unpleasant to exchange them.
Best of luck.

I forgot to mention - when I had my baby, my straight cismale roommate asked if he could have my maternity cargo pants, and he wore them all the time. He was a short and stocky guy, not overweight, and the pants looked fine on him with the t-shirts he wore. I've given regular women's jeans to my current cismale roommate as well, and as long as they don't have any kind of dramatic fashion cut or sparkles or anything nobody seems to care. So if you do end up getting or keeping some women's stuff it probably won't be a big deal.