lol, yeah that's, like asking a pregnant woman, 'are you fat' ? or having a baby ?

You really don't ASK, and really, neither should they ask you, if your TS. (of course people some times might do) if they are just complete morons and lack social grace. another example is like saying to a woman - 'are you a lesbian' ? hmm. My point is, people should realise where the boundaries are of where they should be allowed to ask such personal questions, and you certainly would never tell anyone you don't really know well. If you feel you have to tell some one, then don't let it be because your seeking their approval, and need to be accepted as a woman, no one needs to tell you who you are, if your not sure yourself, then maybe you should go through the transition yet.
Bottom line, is if they 'know' and ask you, then they really didn't need to ask in the first place, and are just being nosey to get some gossip on you so they can talk to their friends about you

As soon as you reveal your real name to them, well there is the possibility they will start identifying you as that person more, than who you are now, assuming they think your some kind of fraud, a joke, or female impersonator. Its a kind of seeking validation of who they really think you are, and trying to put you in that role of who they think you 'really' are. Of course they will smile and say they totally understand, but really, we know they don't, and nor do they 'really ever' accept us as one of the girls properly again. Meaning you will also always feel like the phoney female in the group, and therefore outside of it. Still feeling outside of it, and 'different' and treated as such. That to me is not a transition to just living your life as a woman, its a failure to be recognised as a woman.
Besides all this, if some one has known you as 'Rebecca, or cindy' or what ever, for a long time, then they won't really need to know if your TS or not, they will just want to know you, for who you ARE.

Catherine.