I can't give much advice on transitioning your clothing because even pre T I was always a masculine, butch lesbian and had been wearing men's clothes exclusively for 14 years or so. But I want to throw in Target as a place to shop. And places like Marshall's, TJ Maxx, Ross etc. These may be regional and geographical depending on where you live though.
Have you ever walked by a mannequin in a store window, usually a menswear one, that had on a outfit that made you think, this has to be marketed to gay guys? The great thing about today's men's fashion is skinny and slim pants are in, form fitting blazers, V necklines, form fitting shoes, etc. You can blur those lines easily. Look at high profile athletes such as Can Newton, Russell Westbrook, and Odell Beckham Jr. I am very into men's fashion. I have a budget and I bargain shop. Secondhand, thrift you name it. I'm very masculine but I rock tightish pants and form fitting shirts to show off my muscular frame. When its warm I wear an ankle length pant with no socks. In the winter cable knit, cowl neck sweaters. That sort of thing. But if you shop smart you can achieve a unisex, gender neutral style. Use that to transition your wardrobe.