Thanks for all the feedback, everyone.

After reflecting on your advice and discussing this further with the most awesome member of our Board, I've come to a decision: I've asked that everyone respect my privacy by not bringing up my history in conversation with new staff members, suppliers etc.
However, if new staff members happen to ask why I look and sound relatively feminine at the moment, my colleagues will simply tell them that I'm trans (without going into detail about my history etc.); let them know I'm happy to answer questions if they have any; and ask them to keep this info confidential.
We'll see how that goes.