You would be surprised how easy it is to speak to suppliers about your needs. At the end of the day, they make their money by selling stuff. They are therefore equally happy to sell to t*girls as they are to other women and none of the shops or retailiers listed below would be at all surprised to receive a call from someone with a 'masculine voice' asking questions about sizes, returns policy, stock levels and so on.
When browsing, in particular, underwear or lingerie shops, remember that the t*girls' figures are not the same as the typical woman: we have broader shoulders and no real hips to speak of, and we tend to be longer (taller). Look carefully at the shape of the garment and think where it would sit on your body before diving in to buy it. Also, if you are using breastforms, remember that your bra will need to cover them up as much as possible, otherwise they will look a bit obvious.
