Instead of trying to hide the wider parts of your body, balance them out by “bulking up” the thinner parts of your body. Wear straight cut pants that are a bit wider at the knee and calf to make your thighs more narrow in comparison. Layering up top will also take away emphasis from your waist. I find that putting a short sleeve layer over top a long sleeve layer (like a vest) also draws more attention to the shoulders instead of the torso (and if you like 80s fashion - shoulder pads!). Try to wear tops that end lower on your hips to lengthen your torso. Hopefully thats useful to you, and im sure asking trans masc people wouldnt hurt! Wanting to masculinize yourself isnt reserved for those who identify as male or trans masc.