An outside the box sugguestion, but if you are on facebook, there is a group called "Sounds like you need to be educated on transgender individuals but ok" that is aimed at providing a safe and appropriate place to ask transgender volunteers exactly this type of question. Despite the cheeky name, the people there are very kind and happy to answer well meaning questions that are probably too invasive to ask your transgender acquaintances. —
Meg 26 secs ago